Anatomy And Physiology For Radiographers Ed. 2nd

Anatomy and Physiology
for Radiographers

G. K. WARRICK

M.B., B.S. (l.OND.), M.R.C:.P., F.R.C.S. (k) F.F.R., D.M.R.

Ra(/iol(i^tst-in-(!lfar^e, Royal Victoria Infirmary, Newcastle upon Tyne;
Lcduret in Radioing' and Radiol oiiical Anatomy, (University of Newcastle
upon Tyne: Adv sot in Radiology to No. / Regional Hospital Board and
Honotary Adnsot in Radiology to Siena Leone

\ -DWARD ARNOLD (PUBLISHERS) L PD. LONDON

First Published^ i88r.
Second Rditwn^ 1885/

PRINTED IN GREAT BRITAIN IN THE CITY OF OXFORD
AT THE ALDEN PRESS

Preface to Second Edition

In this edition revision of the text has been carried out, there has
been some rearrangement of subject matter and certain sections
have been rewritten or expanded. The author is grateful to Dr. Paul
Dee for his many valuable suggestions particularly with regard to
the chapter on the Endocrine System which Dr. Dee has largely
rewritten and to bij ^ecreUi^, Miss Sybil Wiper, for her help.
Several new illustrations 'hdVe been added for many of which the
author is indebted to Miss Dorothy Mustart, a.t.d.

The Society of Radiographers has graciously allowed the author
to include in Advice to Student Radiographers (p. viii) comments
which have been made by the Society’s examiners.

It is the earnest hope of the author that this small book will
continue to be of use to the student radiographer and other medical
auxiliaries.

C. K. Warrick

Preface to First Edition

This book is intended primarily for candidates studying for Part I
of the M.S.R. examination. It meets the requirements of the by
syllabus. Material on Radiographic Anatomy and the Biological
effects of Radiation has been included to add to the general use-
fulness and interest of the book and sections on ossification of the
various regions are provided for reference although not required by
the current syllabus.

The author’s thanks arc due to his many colleagues who have
given permission to reproduce illustrations from the following books :
Anatomy and Physiology for Nurses by W. G. Sears, Anatomy for Students
and Teachers of Physical Education by J. W. Perrott, Anatomy and
Physiology for Students of Physiotherapy, Occupational Therapy and
Gymnastics by C. F. V. Smout and R. J. S. McDowall, Anatomy for
Dental Students by M. L. Keene and J. Whillis, Practical Anatomy by
Sir Wilfred Le Gros Clark.

The author is indebted to Dr. Arnold Appleby and Mrs. R. I.
McCallum for their interest and help in correcting the manuscript.

C. K. Warrick

Contents

Advice to student radiographers viii

Chap, i . General anatomical terms i

2. Cell structure and function. The sex cells. Early

development 4

3. The tissues. The systems. The skin. Cartilage and

bone. Some biological effects of radiation 9

4. Bacteria. Inflammation. Infection. Antisepsis and

Asepsis. Ulceration. Neoplasms 25

5. Bones. The skeleton. Joints 30

(). The bones and joints of the skull. The hyoid 37

7. The bones and joints of the vertebral column and

thorax 58

8. The bones and joints of the appendicular skeleton 74

9. The muscular system 107

10. The heart. The blood vessels. The blood. Some

effects of radiation on the blood 1 1 9

11. The respiratory system 145

12. The lymphatic system. The reticulo -endothelial

system 1 58

13. The alimentary system 169

14. The urinary system 209

15. The reproductive system 218

16. The endocrine system 230

17. The nervous system 241

18. The special senses 257

19. Surface anatomy and surface markings 265

Index 273

Advice to Student Radiographers

The best way in which to commit to memory the material covered
in class is to read the subject up as soon as possible whilst it is still
fresh in the student’s mind. The student should take every oppor-
tunity he can of studying the bones and handling models of
anatomical structures.

Some of the questions in Part i of the M.S.R. include a supple-
mentary question on pathology which the examiners expect to be
answered very simply. I’he student is ad\dsed, in this connection,
to study the patient’s request card or radiotherapy notes, etc., to
ask questions of his seniors and to carry about with him and refer
frequently to one of the small books on pathological terms and
definitions recommended by the Society.

The examiners repeatedly comment on the phonetic spelling of
scientific terms which suggests that there is insufficient use of text-books.

In the examination clear anatomical drawings are required and
not drawings of radiographic appearances. The student must be very
careful to read the question carefully and to avoid irrelevant
material in his answer.

In illustrating synovial joints it has been suggested that in their
homework and in the Examination candidates should use the
colours which standard anatomical works use for the synovial
membrane (red), the articular cartilage (yellow) and the capsule
(blue). Further, the synovial joint should be described in the order
indicated on p. 34.

In describing an organ the candidate should try to do so in the
following order:

1. Position 5. Important relations

2. Shape 6. Structure

3. Size 7. Blood and nerve supply

4. Leading from . . . to . . . 8. Lymph drainage

I

General Anatomical Terms

Human anatomy is tlie naked eye study of the structure of the
body; the study of the minute structure of the tissues as revealed by
the microscope is called histology. Human physiology is the study
of the functions of the normal body and pathology is concerned with
diseases and the changes resulting from them.

The body consists of the head, the neck, the trunk and the four
linil3s. 7'hc trunk is divided into the thorax, in which arc the heart
and lungs, and the abdomen. In the upper part of the latter are the
kidneys, the liver, the spleen and most of the digestive system; in
the lower part, called the pelvis, arc the rectum, the bladder and
(in the female) the organs of reproduction.

Each upper limb consists of the arm, the forearm, the hand, the
thumb and the four fingersf The thumb is the first digit and the
little finger is the fifth. Each lower limb consists of the thigh, the
leg, the foot and the toes.

For the purposes of anatomical description it is usual to consider
the body as iHt were always in a standard position, namely, standing
erect facin g tbe obseTver with the arms hanging by the sides and tl:^ ~
palms ot the hands facing forwards. |With the body in this ‘anatomi-
cal’ position It is possible to define certain terms which are in con-
stant use in anatomical descriptions.

The front of the body is its anterior surface^ the back is its posterior
surface^ the head is at the superior or cranial end and the feet are at the
inferior or caudal {tail) end of the body. Structures lying nearer the
midline are said to be medial to those which are lateral and lie further
from the midline. In the limbs the underlying bones give their
names to alternative descriptions for medial and lateral — for
example, in the forearm the medial and lateral sides may be called
the ulnar and radial respectively and the medial and lateral sides of
the leg may also be called the tibial and fibular.

Parts of the limbs which lie nearer the trunk are said to be proximal to
those which, lying further away, are said to be distal or peripheral. Thus
the knee is distal to the hip and the elbow is proximal to the wrist.

2 GENERAL ANATOMICAL TERMS

The anterior surface of the hand is called the palmar surface and
the posterior surface or back of the hand is called the dorsum.

Mldtine or
sogittai piano

The vertical plane which passes through the midline of the body
dividing it into right and left halves is the median or, as it passes
through the sagittal suture of the skull, the sagittal plane. The vertical

GENERAL ANATOMICAL TERMS 3

plane which passes through the coronal suture of the skull at right
angles to the sagittal is the coronal plane. Planes parallel to these are
also called sagittal and coronal respectively. Transverse or horizontal
planes through which cross sections of the body may be made are at
right angles to both the vertical planes.

Fig. i.u Transverse section through the trunk showing the
sagittal and coronal pljfi^es.

A subject in the supine position is lying on his back. One in the
prone position is lying face down.

The posterior (or anteroposterior or A.P.) radiographic projection
means that the posterior surface of the patient or limb is nearest the
film. The anterior (or poslero-anterior or P.A.) projection is taken in
the reverse way with the anterior surface of the patient or limb
nearest the radiograph.

2

Cell Structure and Function

The human body is composed of tissues which are made up of
cells of various kinds (c.g. nerve-cells, muscle-cells, etc.) and the
extracellular material, most copious in fibrous tissue, cartilage and
bone, which the cells produce. Cells are so small that they can only
be studied with powerful microscopes but each is a tiny living organ-
ism which exhibits many of the properties of the body as a whole.

A cell consists of protoplasm which is a colourless jelly-like sub-
stance composed of water, mineral salts, and complex organic
compounds called proteins. By the use of certain staining methods
the microscope reveals that the protoplasm of the cell is a delicate
reticulum (network) containing within its meshes a more fluid

Fig. 2.1 The* general structure of a cell.

portion. Most cells are surrounded by a thin membrane which is
permeable to certain substances so that nutritious material may
enter it and waste products may leave. Near the centre of the cell is
a globular structure known as the nucleus, the living matter of the cell
apart from the nucleus is called the cytoplasm.

The nucleus contains a number of small rod-like structures called
chromosomes upon which the life of the cell depends. Chromosomes are
of extremely small size and they can only be studied by powerful
microscopes after being specially stained. In human cell nuclei there
are forty-six chromosomes grouped into twenty-three pairs; at
particular points along theiti they possess structures termed genes
which transmit hereditary characteristics.

Scientists and philosophers cannot satisfactorily define life but it
is possible to enumerate some of the activities which characterize

4

CELL STRUCTURE AND FUNCTION 5

living things. All living organisms require to breathe, all must feed,
i\\ need to excrete their waste products, all are able to reproduce and
all exhibit some degree of irritability and contractility.

These activities must be studied in greater detail.

1. Respiration. The energy required for the activities of the
body is obtained from the breaking down of food products by
oxidation. This process requires oxygen, and carbon dioxide is
produced as a waste product ; the means by which oxygen is supplied
and carbon dioxide is removed is known as respiration.

2. Digestion. The energy the body expends and the material
required for growth and the replacement of cells and tissues arc
derived from the food which it is the function of the alimentary
canal to take in, digest and absorb. Digestion is the process of
converting the food into a form in which it can be absorbed through
the intestinal wall to enter the blood stream. It is performed by
enzymes or ferments which are present in the saliva and in the
gastric, intestinal and pancreatic juices.

3. Metabolism. A cell obtains from its food both the energy to
perform its function and the material from which to make new
protoplasm either for growjh or for making good the effects of wear
and tear. The chemical processes by which food is converted into
energy or new protoplasm are called metaholism. It is usual to
subdivide metabolism into the building up processes - anabolism^
and the breaking down processes which result in the production of
heat or the performance of work which are known as catabolism,

4. Excretion. The metabolic processes in, the cell result in the
production of waste products or excreta which consist mainly of *

A

B

Fig. 2.2 Cell division by mitosis.

A Cell before mitosis showing nucleus. B During mitosis, the
nucleus has become spindle-shaped and the chromosomes, shown by
denser lines, have split longitudinally and are migrating to its oppos-
ite poles. C The nucleus and cell are dividing into two and the two
daughter cells being formed will each have a full complement of
chromosomes.

b CELL STRUCTURE AND FUNCTION

nitrogenous matter such as urea and uric acid, water and carbon
dioxide. These pass through the cell wall into the tissue fluid which
surrounds it and so reach the blood stream. Nitrogenous excreta and
water are extracted from the blood by the kidneys, jhe skin excretes
water in the form of sweat and the lungs excrete carbon dioxide
and water.

5. Reproduction. Cells multiply by dividing into two by a com-
plex process known as mitosis. In order that the two daughter cells
so formed may each contain its share of chromosomes the in-
dividual chromosomes split longitudinally into two during the
process of cell division. Thus the total number of chromosomes in
the daughter cells is the same as in the parent cells.

6. Irritability and contractility. The power of an organism to
respond to stimuli and to adapt itself to its surroundings depends on
its irritability and contractility. In the higher animals cells vary in
their responses to stimuli. A muscle-cell responds by contracting, a
gland by secreting, the cells of the retina of the eye respond to the
stimulus of light and those of the ear to sound.

PtMudopodlum

Fig. 2.3 The amoeba. Illustrating the mode of progression known
as amoeboid movement.

In the human body some cells, muscle-cells for example, show a
high degree of contractility and others, such as the white blood
corpuscles, exhibit a type of movement called amoeboid. This takes
its name from the amoeba^ a microscopic unicellular organism living
in pond water which progresses by throwing out a protoplasmic
process or pseudopodium (‘false foot’) in the direction in which it
desires to go. The protoplasm is withdrawn from the opposite side
of the cell and flows into the pseudopodium which represents the
new position of the cell.

The Sex Cells, Fertilization and Early Development

In the human being, as in most animals, a new individual arises
as a result of fusion of a single cell derived from the male parent
with one derived from the female. These are known as the sper-
matozoon and ovum respectively. The fusion of the spermatozoon and

CELL STRUCTURE AND FUNCTION 7

tlje ovum results in fertilization of the latter. The spermatozoon and
the ovum have arisen by a special form of cellular reproduction
distinct from mitosis termed miosis. The cells resulting from meiotic
division only contain half the number of chromosomes typical for the
cells of the species so that when the ovum is fertilized the full com-
plement of forty-six chromosomes is restored. The fertilized ovum
has thus obtained half its chromosomes from the male parent and
half from the female parent. The chromosomes will determine the
make-up of the individual, for example, whether he has blue eyes or
brown eyes, the shape of the ears, the colour of the skin, etc., and
whilst the individual will not be exactly like either parent it is a
matter of common observation that the certain physical and mental
characteristics of parents seem manifested in their offspring.

The spermatozoon^ of which many millions are produced at each
ejaculation, is a tadpole-like unicellular structure consisting of a
head part in which is the nucleus, a middle part and highly active
tail. The spermatozoon propels itself by vigorous action of its tail
from the vaginal vault where it will have been deposited to the
uterine tube where it is capable of surviving for a few days, during
which it may meet and fertilize an ovum.

The ovum is a large cell which is shed monthly by the
ovary at the time of ovulation (p. 226). The ovum is
believed to attract spermatozoa by some form of chem-
ical action, a process known as chemotaxis. The ovum is
carried by ciliary action along the uterine tube where
it may encounter spermatozoa. The first spermatozoon
to reach the ovum will fuse with it and thus fertilize it.

The fertilized ovum, with its full complement of
forty-six chromosomes, divides by mitosis into two
cells, so that four, eight, sixteen and thirty-two cells,
etc., etc., are produced. The mulberry-shaped mass of
cells thus formed (the morula) buries itself in the wall of
the uterus and as division proceeds it becomes hollowed
out into a relatively thin-walled, fluid-filled structure, the blastocyst.
At one pole of the blastocyst is a mass of cells in which two cavities
soon form; one is the amniotic cavity and the other ihcyolk sac. Inter-
vening between them is the embryonic plate where the embryo itself
develops; the amniotic cavity enlarges very greatly bathing the
embryo in its fluid contents and completely filling the enlarging
uterus.

On the exterior of the blastocyst a number of finger-like processes
known as villi project and anchor it to the uterus; later these take

Fig. 2.4 Sper-
matozoon or
male sex cell.

8

CELL STRUCTURE AND FUNCTION

4 Blastocyst

Fig. 2.5 Segmentation of the o\aim leading to tlie formation of the morula (3)
and the blastocyst (4).

part in the formation of the placenta. The foetus^ as the human em-
bryo is called after the eighth week, is connected by the umbilical
cord to the placenta where gaseous and other interchanges take
place between the maternal and foetal circulations but no actual
mixing of the blood occurs.

The embryonic plate consists of three layers of cells known as the
ectoderm, the endoderm and the mesoderm. These are the three
germ layers from which all the tissues of the body develop. The
ectoderm gives rise to the skin and the nervous system; the endoderm
to the epithelial lining of the alimentary, the respiratory and the
urinary tracts. The mesoderm forms the connective tissues which in-
clude the skeletal system and the muscles and it also forms the blood
vessels and most of the organs of the body.

By the eighth week the embryo has grown to about i inch in
length; after this it is known as the foetus and it attains the length
of about 8 inches by the sixteenth week. At this time there is usually
sufficient calcium in the skeleton for the presence of the foetus to be
demonstrated by radiography. The mother becomes aware of foetal
movements by the twentieth week and birth occurs at about the
fortieth week.

3

The Tissues. The Systems. The Skin. Car-
tilage and Bone. Some Biological Effects of
Radiation '

THE TISSUES

Just as a wall may be built of similar bricks so are the tissues
forrtied of collections or aggregations of similar cells. It is usual to
recognize four essential tissues:

1. Epithelial tissue.

2. Connective tissue.

3. Muscular tissue.

4. Nervous tissue.

Some of these tissues consist not only of cells but of varying
amounts of extracellular material which the cells produce. Fibrous
tissue, cartilage and bone have a conspicuous amount of extra-
cellular material in their composition (see below).

I. Epithelial tissue is composed of closely packed cells with
sparse extracellular material between them and its function varies
with its situation so that it may be found acting in a protective, a
secretory, an absorptive or an excretory role.

It is usual to classify epithelial tissue into simple, consisting of a
sipgle layer of flattened cubical or columnar cells, and compound,
which is composed of several or many layers of cells.

Simple epithelium is found lining the glomeruli of the kidneys, the
air cells of the lungs and the surfaces of the peritoneum and pleura
and forming the walls of capillaries. Ciliated columnar epithelium is a
variety of simple epithelium composed of columnar cells with fine
projections (cilia) from their free surface and it is found in the
respiratory tract and the uterine tutesT The movements of the
cilia result in the propulsion in one direction of material in contact
with the epithelium and it is by this method that material is expelled
from the accessory nas^l sinuses.

B

9

10

THE TISSUES

The secretory glands of the body are composed of cubical or
columnar epithelium and their secretions are passed either directly
into the blood stream (the ductless glands, Chapter i6) or through
a duct (a narrow tubular structure) on to the surface of the skin or
mucous membrane. The latter group are called the glands of
external secretion and the simplest type is shaped like a test-tube
whose walls are made up of cubical or columnar cells. The secretions
of these cells are passed into the ‘tube’ and so reach the appropriate
surface. The simple tube-like arrangement may be elaborated by
elongation and coiling (e.g. sweat glands) or by a multiplicity of
simple tubes opening into a common duct (e.g. salivary glands).

Squamous

epitheUum

9

9l§

Ciliated columnar
epithelium

mmiiBii/iMS

mmmmi

Striped muscle
fibres

Unstriped muscle
fibres

Heart muscle
fibres

Fig. 3.1 Some of the different kinds of cells found in human tissues.

Compomd epithelium is fQund commonly in two forms : the stratified
squamous epithelium which makes up the epidermis of the skin and the
mucous membrane lining the mouth, pharynx and oesophagus, and
the transitional epithelium found in the bladder and ureters.

THE TISSUES

It

2.0 Connective tissue is the most widely spread of all human
tissues and its function is to provide a supporting framework for
individual organs and for the body as a whole. Connective tissue is
characterized by the abundance of extracellular material and the
relative sparsity of its cells. White fibrous tissue is made up of bundles
of fibres and is the chief component of tendons and ligaments.
Elastic tissue contains elastic fibres in addition to white fibrous tissue
and is found in the arteries, bronchioles and vocal cords. Areolar^
tissue^ often described as packing tissue, is found in the subcutaneous
tissues, beneath mucosal surfaces and surrounding the blood vessels.
It consists of a combination of fibrous tissue, elastic tissue and
gelatinous material. Fatty tissue is composed of cells which contain
globules of fat. Blood emA lymph are tissues in which the extracellular
material is completely fluid and the cells are carried round the body

Fig. 3.2 Types of glands;

A Simple tubular; B Coiled tubular;
C Branched tubular; D Racemose.

in the moving stream. In cartilage and bone the extracellular sub-
stance is solidified and in bone mineral salts are deposited in it.

3. Muscular tissue is composed of bundles of fibres and three
types are usually recognized. Striped or voluntary muscle takes its name
from the fact that its fibres show transverse stripes when it is examined
with the microscope. Unstriped or involuntary muscle is found in organs
not under voluntary control such as the intestines, urinary tract and
uterus and its fibres do not show transverse stripes. Heart muscle is
grouped separately although it is involuntary muscle, for the fibres,
although different from voluntary muscle, do show transverse
stripes.

4. Nervous tissue is composed of nerve-cells, nerve-fibres and a
special type of connective tissue called neuroglia. The nerve-cells are

THE tissues

found in ganglia and in the grey matter of the central nervous
system; they receive and store impressions and initiate outgoing
impulses which are conducted to and from the cell at varying speeds
along the fibres. A nerve-cell and its fibres constitute a neuron and
usually only one process, the axon, conducts impulses from the cell
but often several, called dendrons, conduct impulses towards the cell.
Nerve-cells, like muscle-cells, are incapable of reproduction and
^ therefore after destruction they cannot be replaced.

Membranes

Thin layers of tissue which line body cavities are called mem-
branes. The most important of these are (i) mucous, (2) serous,
(3) synovial.

( 1 ) Mucous membranes line the nose, the mouth, the respiratory and
the alimentary systems, the bladder, the ureters and the urethra,
etc. They are composed of simple and compound epithelia of which
the cells may be squamous, columnar, ciliated, etc., and some of the
cells produce mucus which has a lubricating and protective function.

(2) Serous membranes are those which line the large body cavities,
namely, the pleura, the pericardium and the peritoneum. They are
composed of a single layer of squamous epithelium with a connective
tissue base. The surfaces are kept slightly moist and enable the
structures which they cover to glide over each other with a minimum
of friction.

(3) Synovial membranes are structurally similar to the serous
membranes and line the capsules of joints and the sheaths of
tendons. They are slightly moist and enable movements of joints
and tendons to occur without friction.

THE SYSTEMS

The various tissues in different combinations form the organs and
structures of the body which can be grouped into a number of
systems.

1. The locomotor system: the bony and cartilaginous skeleton, the
joints and muscles.

2. The circulatory system: the heart and the blood vessels.

3. The respiratory system : the larynx, the trachea, the bronchi and
the lungs.

THE SKIN

*3

4. «The digestive or alimentary system: the alimentary canal and

associated structures such as the salivary glands, the liver, the biliary
apparatus and the pancreas. ^

5. The urogenital system: the organs of urinary excretion and those
of reproduction.

6. The endocrine system: the ductless glands.

7. The lymphatic system: the lymph vessels and nodes.

8. I’he nervous system, the brain, the spinal cord and nerves. ^

9. The reticulo-endothelial system.

V

It is now proposed to study in more detail the skin, cartilage and
bone. The blood will be considered with the Circulatory System
(Chapter 10).

THE SKIN

The skin covers the surface of the body and is continuous with the
mucous membranes at the various orifices. It consists of two layers;
the more superficial, the epickrmis, is composed of stratified squa-
mous epithelium and is devoid of blood vessels. The deeper layer is
the dermis or true skin and consists of vascular connective tissue in
which cells are relatively scanty.

The epidermis is -made up of a horny zone and a germinal zone.

The horny zone is composed of three different layers.

(1) The horny layer (or stratum corneum) is the most superficial
and consists of dead cells whose protoplasm has been converted into
a horny substance called keratin. This layer is thickest on the palms
of the hands and the soles of the feet.

(2) The clear layer (or stratum lucidum) also consists of dead cells
which have completely lost their nuclei.

(3) The granular layer (or stratum granulosum) is the deepest
layer of the horny zone; the cells of which it is composed are
degenerating, their cytoplasm has become granular but their nuclei
are still visible.

The germinal zone is composed of two layers.

(i) The prickle cell layer lies immediately deep to the granular
layer and is composed of sheets of cells which have thorn-like
projections, hence the name prickle cell. These cells are alive but
they do not usually reproduce.

H

THE TISSUES

(2) The basal layer is the deepest layer of the epidermis and it
consists of a layer of columnar cells. This single layer of cells is the
only epidermal layer whose cells reproduce in healthy skin. All the

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cells the basal layer gives rise to arc gradually displaced super-
ficially and as they move towards the surface they progressively
degenerate passing from dne layer to the next until they are ulti-
mately shed. The pigment which is responsible for freckles, sun-tan
and the colour of the skin in dark-skinned races is situated in the
basal and in the deepest parts of the prickle cell layers.

THE SKIN

*5

Tlje dermis varies considerably in thickness; it is thickest on the
palms of the hands and soles of the feet and thin in the skin of the
male genitalia and eyelids. Two layers are recognizable in the
dermis :

(1) The papillary layer consists of numerous highly sensitive
microscopic conical projections called papillae which are in direct
contact superficially with the basal layer of the epidermis. The
distribution of these papillae is responsible for the lines and ridgest
of the epidermis, which differ from one individual to another and
form the basis for the study of finger prints in criminology.

(2) The reticular layer is made up of interlacing bands of fibrous

Fig. 3.4 Diagram showing the layers of the epidermis.

tissue and lies deep to the papillary layer. In this layer are found the
hair follicles, sweat glands, tactile corpuscles (for sensation, see page
263) and sebaceous glands (grease secreting). Below the reticular
layer is the subcutaneous tissue which usually contains fat and
separates the skin from the deep fascia and muscles.

The appendages of the skin are the nails, the hairs, the sweat glands
and the sebaceous glands.

The nails arise from the epidermis and are principally composed
of a greatly thickened clear cell layer. Hairs lie in follicles which dip
deeply into the dermis. The sebaceous glands open into the follicles
and secrete a greasy substance sebum. The sweat glands each consist of
a long tube which is coiled iii its deeper part.

l6 THE TISSUES

THE FUNCTIONS OF THE SKIN

The skin forms a waterproof covering for the body protecting it
from mechanical, chemical, bacterial action, etc., and it possesses
great powers of regeneration which are, of course, cftnstantly called
upon to make good the effects of wear and tear upon it. It gives
origin to the hair and nails and is modified in particular parts being
very thin over the eyelids and very thick on the palms of the hands
* and soles of the feet. It has considerable inherent elasticity.

It is an important sense organ providing information about the
environment particularly with regard to cold, heat, pain and touch
which have special end-organs.

It has the ability to secrete sweat and sebum and as some of the
constituents of sweat are waste products it acts as an excretory organ.
Sweat consists of water, a small proportion of sodium chloride and
traces of excreta.

The principal reason for the secretion of sweat is concerned with
the function of the skin to assist in the regulation of body temper-
ature. Body heat is produced by metabolic processes and muscular
activity and most of the heat of the body is lost through the skin. The
heat regulating centre of the brain controls heat-loss by altering the
calibre of the arterioles of the dermis and so varying the blood flow
through the skin. The alteration in calibre of the arterioles is effected
through their autonomic nerve supply so that stimulation of the
sympathetic nervous system causes constriction of the cutaneous
arterioles whereas parasympathetic stimulation causes dilation of
cutaneous arterioles and increased heat-loss.

Another function of the skin is the synthesis of vitamin D. This
occurs under the influence of sunlight and constitutes an alternative
source of this vitamin which is also present in the food and plays a
very important part in the growth of bone (see p. 22). This function
of the skin explains why rickets was formerly so common in children
living in dark and overcrowded slums, deprived of sunlight and
subsisting on a diet deficient in those foods which are richest in
vitamin D, namely, butter, milk,' Cod-liver oil, etc.

CARTILAGE AND BONE

(^Cartilage and bone are connective tissues consisting of a large
proportion of resilient extracellular material which, in the case of
bone, becomes impregnated with mineral salts. Most of the bones
of the body are first formed in cartilage which is converted into bone
by a process known as ossification.^^

CARTILAGE

n

Cartilage is a gristly substance in which cells lie in small groups
and it is devoid of blood supply. There are three chief types of
cartilage :

/ I . Hyaline cartilage. This is a smooth almost transparent material
usually found covering the ends of the long bones where it is known
as articular cartilage ; it is also found in the nose, larynx, trachea and

This consists of cartilage strengthened by«
fibrous tissue. It is found in the spinal inter-
vertebral discs and in the semilunar cartilages within the knee. )

b^ronchi.

^2. Fibrocartilage.
bundles of white

Fig. 3.5 Fibrocartilage.

3. Elastic cartilage. This is a combination of cartilage and elastic
tissue and is found in such structures as the external ear (pinna) and
the epiglottis.

Cartilage often becomes impregnated with calcium salts which
render it opaque to X-rays. Thus the costal cartilages and the
cartilages of the larynx are often demonstrable in radiographs.
This calcification is not a disease process nor is it to be confused with
the conversion of cartilage into bone (ossification) which is a much
more complex process. \

Bone is an extremely hard but slightly elastic variety of connective
tissue which is made up of organic and inorganic components. The
former consist of cells called osteoblasts and bundles of fibres lying

i8

THE TISSUES

in a ground substance or matrix. The inorganic component consists
of calcium phosphate and carbonate and other mineral salts which
are laid down in the matrix. This dual composition of bone is of
great importance. The organic material may be reanoved from a
bone by burning it, leaving a brittle light structure consisting only
of mineral matter. The inorganic or mineral part may be removed
by soaking the bone in acid so that it becomes decalcified. Such a
^ ^decalcified bone consists only of organic matter which is flexible and
rubbery and a bone like a rib may be tied into a knot after it has
been decalcified.

STRUCTURE OF BONE

If a bone is cut transversely it will be seen that there is an outer
layer of compact bone of dense ivory-like consistency, an inner layer of
cancellous or spongy bone and a central medullary or marrow cavity.

Fig. 3.6 Transverse section of compact bone showing Haversian systems.

Compact bone is seen under the microscope to consist of many
similar units called Haversian systems. These have a central Haversian
canal containing blood vessels, nerves and lymphatics and around
the canal are concentric layers of bone running longitudinally called
lamellae. In the lamellae are small cavities, the lacunae, where the
bone-cells {osteoblasts) live and these are connected by fine canals
{canaliculi) which cross the lamellae.

BONE

*9

Cstncellous or spongy bone is microscopically similar but consists
of a network of lamellae in the interstices of which is the bone marrow.
The marrow fills the medullary cavities and is of two types, red and
yellow. Red marrow is the source of most of the blood cells (see
p. 167) and in infancy this variety predominates. Yellow marrow is
fatty tissue and in adult life it replaces red marrow in the long bones
since, after childhood and adolescence are past, blood cells, in
healthy individuals, are formed in the flat bones only.

Surrounding the compact bone is the periosteum which has an inner'
osteogenic or bone-forming layer and an outer fibrous layer. The

Fig. 3.7 Longitudinal section from the human
ulna, showing Haversian canals, lacunae and
canaliculi (Rollet).

periosteum is a vascular structure and sends vessels into the under-
lying cortex. In addition to the periosteal vessels the long bones
receive blood from a nutrient artery which enters through a short canal
often visible in radiographs. The ends of the long bones also receive
vessels from those which run in the capsules of the joints of which
they form part.

DEVELOPMENT AND GROWTH OF BONE

Most bones develop from rods or masses of cartilage but some,
such as thos? of the skull, are preceded not by cartilage but by

20

THE TISSUES

membrane. Thus ossification may be described as being intra-
cartilaginous and intramembranous. There is no essential difference
in the process of ossification occurring in these two ways and only
the former will be described in greater detail. •

SECONOARY CENTRES OF OSSIFICATION AND BONE FORMED FROM THEM
MEDULLARY CANAL

Reproduced by permission from Mitcheli and Patterson: * Basic Anatomy*

(£. and S. Livingstone)

Fig. 3.8 Ossification in cartilage

Intracartilaginous ossification. In the early weeks of intrauterine life
buds are formed on the embryo ^t the sites of the future limbs.
Within these limb-buds rods of cartilage develop and by the sixth

60N£:

21

weck^of foetal life a complete cartilaginous model of the skeleton has
been formed. The cartilage has next to be converted into bone. This
is a gradual process starting, in the case of a future long bone, with
the appearance of a primary centre of ossification in the middle of the
shaft or diaphysis. Here calcium is laid down, cartilage-cells die and
bone-cells [osteoblasts) appear. By the activities ofthese osteoblasts and
the canalizing of the newly formed bone by osteoclasts (bone de-
stroyers) the characteristic structure of bone is produced. This process
spreads outwards from the primary centre and ultimately involves
the whole shaft.

Hyaline cartilage

Epiphysis

Epiphyseal plate
of cartilage

Cancellous
(spongy) bone

Periosteum

Compact (ivory)
bone of shaft

Bone marrow

Fig. 3.9 Longitudinal section through
the shaft and epiphysis of a long bone.

Secondary centres of ossification appear in the ends of the
bones or epiphyses (sing, epiphysis) and until growth in length is
complete a cartilaginous epiphyseal plate separates the epiphysis
from the diaphysis. A radiograph during childhood shows this plate
as an apparent gap, the ‘epiphyseal line’ between the shaft and the
epiphysis.

22

THE TISSUES

Growth in length of the bone occurs during childhood by the
production of bone at the epiphyseal plate in the area known as
the metaphysis which is simply the end of the shaft adjacent to the
epiphysis. Growth in length of a long bone occurs more at one end
than at the other. Thus in the lower limb most growth occurs in the
region of the knee, so that the lower ends of the femora and the
upper ends of the tibiae and fibulae grow more rapidly than the hip
^and ankle regions. In the upper limb bone growth is less at the
elbow than at the shoulder and wrist.

Simultaneously with growth in length there is also growth in
circumference resulting from the laying down of bone by the
osteogenic layer of the periosteum. In this connection it is of interest
to note that if a bone is shelled out from its periosteum (sub-
periosteal resection) a new shaft may be formed by the osteogenic
layer of the periosteum.

As a bone grows in length the ends are carried further apart and
since the form of the bone is maintained a certain amount of
remodelling occurs. This is carried out by osteoclasts.

FACTORS CONTROLLING BONE GROWTH

In life bone is constantly being laid down and it is being con-
stantly destroyed. These processes occur simultaneously and their
balance depends on various factors which, if disturbed, may pro-
foundly affect the appearance and strength of the bone.

For normal bone growth to occur there must be an adequate
intake of mineral salts, especially calcium and phosphorous, in the
diet. Vitamin D is necessary for the absorption of calcium from the
bowel and a deficiency of this vitamin results in a disturbance of
ossification known as rickets. Certain ductless glands influence bone
metabolism and in this connection fhe parathyroid glands are the
most important for they regulate the level of the calcium in the
blood and the quantity in the skeleton. Other ductless glands such
as the thyroid and pituitary also exert profound influences upon
bone.

Bone requires the stimulus of normal activity to maintain its
strength and all diagnostic radiographers will be aware that if a
limb is encased in plaster , of Paris for some weeks it becomes much
less radio-opaque — a condition known as disuse osteoporosis.
Another factor of importance in the normal development of a bone
is the absence of injury to the epiphyseal line and to the epiphysis.

SOME BIOLOGICAL EFFECTS OF RADIATION 23

SOME BIOLOGICAL EFFECTS OF RADIATION

X-rays and the gamma rays of radium are called ionizing radiations
because they are able to displace electrons from the atoms of the
matter through which they pass. These ionizing radiations are
injurious to cell structure but the exact way in which they effect this
injury is not known. The cell nucleus is more susceptible than the
cytoplasm and it is especially vulnerable just before the start of,
mitosis. The chromosomes and the genes which they bear may be
injured; the proteins of the cytoplasm and the enzymes which
effect various chemical processes within the cell may also suffer.
Most tissues of the body can withstand the action of ionizing
radiations to some extent and a threshold dose probably exists below
which no harmful effects may be demonstrated. There may be no
threshold dose for the gonads (testes and ovaries) so that even small
doses of radiation may temporarily impair the production of
normal spermatozoa and ova. For this reason and so as to avoid
unnecessary radiation damage to the hereditary mechanism of the
sex cells, the genes and chromosomes, it is desirable to exclude the
gonads from the primary X-rty beam or to shield them with lead
during diagnostic examinations.

In radiotherapy large doses are often given and damage to normal
tissues is unavoidable but by skilful planning of the treatment it is
usually possible to avoid such a degree of damage that permanent
effects of a harmful nature will follow.

The most radiosensitive tissues of the body are lymphoid tissue,
bone marrow, the germinal epithelium of the testes and ovaries, the
ductless glands and the salivary glands. Less sensitive are the skin
and mucous membranes, and least sensitive are bone, muscle and
nerve tissue. The cells of malignant tumours are usually more
sensitive than normal tissues. ^

It is not easy to grasp the meaning of the word dose as applied to
ionizing radiations for the effects of radiation on the body depend
on how big an area of the body is irradiated. Thus if a dose of 500
roentgen units were delivered to a small skin area there might be
a reddening with some loss of hair but no general constitutional
disturbance, yet if the same dose were given to the whole body 50
per cent of the people so irradiated would die. The greater susceptibi-
lity of the body to irradiation of large surface areas is mainly due to
the effects of radiation on the bone marrow with consequent depres-
sion of the production of blood corpuscles.

The constitutional disturbance which follows the administration

THE TISSUES

24

of moderately large doses of radiotherapy to portions of the body
and which in its more severe forms is met with in survivors of
atomic explosions, where bigger doses of whole body radiation are
involved, is called radiation sickness, •

EFFECTS OF RADIATION ON THE SKIN

' The effects of ionizing radiations on the skin arc comparable with
the effects of other rays which inflict burns such as light and heat. In
the past the effect of radiation on the skin was used as a measure of
the amount given — the so-called erythema dose. The changes
produced in the skin depend on whether the radiation is given in a
few relatively large doses (acute irradiation) or in very small doses
repeatedly over a prolonged period (chronic irradiation).

Depending on the dosage the acute effects may resolve completely
or be followed by certain sequelae. A dose of X-rays of from 300 to
400 r units, i.e. smaller than that required to produce permanent
damage, may cause an initial reddening followed by a definite
reddening or erythema in 7 to 10 days. This erythema is often
accompanied by loss of hair but complete recovery may follow.
With larger doses of the order of 1000 to 1500 r units a more severe
erythema is produced which may be accompanied by blistering and
still larger doses may cause ulceration.

The changes due to chronic irradiation may also be met with as
late sequelae to acute irradiation. They may be partly atrophic
(wasting away) and partly hypertrophic (due to overgrowth). The
skin may become dry, shiny and scaly with sparse and ill-formed
hairs, Ijrittle nails and tiny dilated blood vessels known as telan-
giectasis. There is marked susceptibility to injury and ulcers may
form which are resistant to healing; sometimes malignant disease
may supervene. The affected area may also show warty outgrowths
and these, too, may undergo malignant change.

Since the effects of chronic irradiation may not become apparent
for many years radiographers must punctiliously obey the safety
precautions laid down in their departments and in documents such
as the Code of Practice issued by the Ministry of Health. They
should never, under any circumstances, expose their unprotected hands to the
X-ray beam. By the time changes become apparent the succession of
events will be irreversible and irrevocable and the only hope of
averting the consequences may be by plastic surgery.

4

Bacteria. Inflammation. Infection. Anti-
sepsis. Ulceration. Neoplasms.

Bacteria

Bacteria are microscopic unicellular organisms which multiply
very rapidly; they arc widely distributed in nature and are con-
stantly present in the air, water, soil, foodstuffs, etc. Many normally
play important and essential roles in natural processes, e.g. the
nitrogen-fixing bacteria in the leguminous plants and the cellulose-
splitting bacteria which inhabit the large intestines of herbivorous
animals. Only a small propoi^^ion are pathogenic, i.e. capable of
causing disease.

%

ID

A-V

A

6

C

D

C:> ^

^ (b

E

F

Q

G

H

Fig. 4.1 Some Bacteria. A Staphylococci; B Streptococci; G Flagel-
late bacilli; D Spore-bearing bacilli; E Vibrios; F Spirochaetes;

G Non-flagellate bacilli; H Spore- bearing bacilli.

As well as bacteria there are viruses, which are so small that they
can only be seen by the electron microscope which is many thou-
sands of times more powerful than the ordinary light microscope.
Some bacteria can increase their resistance to the defences of the
body by spore formation; a notable example of this is the tetanus
(lock-jaw) bacillus which produces highly resistant spores and pro-
longed sterilization of catgut, dressings, etc., is required to destroy
them.

A simple classification of bacteria is based on their shape.

G 25

26 BACTERIA, INFLAMMATION AND INFECTION

1. Cocci are spherical, measure 1/33,000 of an inch (about ip) ot
less in diameter and are named according to their method of division.
Thus staphylococci form clumps and streptococci form chains.

2. Bacilli are straight or slightly curved rods and some are mobile
because they possess protoplasmic processes called flagella.

3. Vibrios are comma-shaped organisms and are usually actively
motile, e.g. the cholera organism.

y 4. Spirochaetes are spiral organisms and are longer than other
bacteria. Syphilis and a number of tropical diseases are caused by
this type of organism.

Pathogenic bacteria and viruses, many of which produce powerful
poisons or toxins, and parasites (e.g. malaria) and moulds (e.g.
ringworm) are constantly assailing the body which defends itself by
(a) the general or non-specific defences and (6)* the specific defences.

(a). The general defences of the body. The body defends itself against
invading organisms in many ways. These include the possession of
an intact skin and mucous membranes, certain secretions which are
capable of destroying bacteria such as tears, mucus and, especially,
gastric acid. The ciliated epithelium which lines the nasal passages,
trachea and bronchi can eject particulate matter. When organisms
penetrate these barriers they excite an inflammatory reaction by the
body (see below) .

(A). The specific defences of the body. These are concerned with
counteracting the toxins liberated by bacteria and they may be
augmented by artificial means. The introduction of bacteria and
their toxins into the body causes it to produce antibodies. The anti-
bodies combine with the bacteria and bacterial toxins and tend to
neutralize any effects the latter might have on the body. Antibodies
which neutralize toxins are often termed antitoxins. The production
of antibodies confers a variable amount of immunity, for example, it
is very rare to suffer from more than one attack of measles because
the first attack produces almost complete immunity. On the other
hand influenza is followed by a period of only partial immunity
lasting weeks or a few months ^

Immunity to certain infections can be produced artificially by
vaccination in which the patient’s own powers of defence are mobilized
by injecting preparations of dead bacteria or weak strains of the
organism against which protection is desired. Short-term immuniz-
ation can be produced by the administration of antitoxic serum, e.g.
tetanus antitoxic serum is often given to accident cases to protect
them from tetanus (lock-jaw). Antitoxic serum is prepared from the

INFECTION, ANTISEPSIS AND ASEPSIS 27

blood of an animal which has survived the disease and it provides
the recipient with ready-made antibodies.

'inflammation

This is the reaction of the body to irritation by bacterial infection
and physical and chemical injuries. I’he classical signs of in-
flammation are heat, redness, swelling, pain and loss of function.
These signs are the result of an increased blood supply to the area
and transudation of fluid through the vessel walls. An important part
of the inflammatory reaction is the passage of white blood cor-
puscles through the capillary walls into the tissues, where they
collect round the injured, area and are most numerous in cases of
bacterial infection. The white blood cells are phagocytic, which
means that they arc capable of ingesting foreign matter, dead
tissue and bacteria. In most bacterial infections examination of the
blood will disclose an increase in the white blood count, this indicates
a favourable response by the body. Failure to respond in this way
may be a very serious omen. Under favourable circumstances
inflammation may be followe<^ by resolution and repair.

INFECTION

If the inflammatory reaction which is excited by bacterial in-
vasion of the tissues is studied under the microscope an intense
battle between the bacteria and the white blood corpuscles will be
observed. The latter will destroy the bacteria by phagocytosis and
in the process many white blood corpuscles will be killed. Unless
resolution and repair follow, the local death of tissue and the
accumulation of dead leucocytes and dead bacteria will result in the
formation oi pus. If the infection remains localized an abscess may
form and by rupturing through the skin it may produce an ulcer
(see below).

In addition to the local signs of inflammation which may be
present in cases of bacterial infection, varying constitutional symp-
toms will be caused by toxaemia. Some infections may give rise to an
acute illness (i.e. one of short duration) like pneumonia, influenza or
boils; others cause chronic (i.e. long continued) illness. Amongst the
latter are such conditions as tuberculosis, syphilis and actinomycosis.

"ANTISEPSIS AND ASEPSIS

As a result of the wbrk of Louis Pasteur it was established that

28

ULCERATION, NEOPLASMS

bacteria are the cause of wound infection and Lord Lister intro-
duced the antiseptic method of surgery, in which stress was laid not
on excluding bacteria from the wound but on killing any which were
present. Thus the vicinity of the wound was sprayect with carbolic
and the instruments and towels were soaked in this substance.
Chemicals which inhibit the growth of organisms are likely to
damage the tissues, the patient and others in the neighbourhood
and so the antiseptic method was replaced by the aseptic. In this
method all organisms are excluded as far as possible from the
operation area by strict cleanliness, the use of sterilized (germ free)
instruments, the thorough cleansing of the patient’s skin and the use
of rubber gloves, etc., by the surgeon.

Sterilization is usually performed by exposure to heat or by
immersion in antiseptics. Exposure to heat takes various forms.
Most bacteria are destroyed by boiling for five minutes but this is not
long enough for sterilization of instrume^nts, etc., since boiling
for twenty minutes is required to destroy the spores of certain
organisms. Steam under pressure in an appliance called an auto-
clave is widely used and exposure for 15 minutes to a pressure of
15 lb. per square inch above atmospheric pressure raises the boiling
point of water to 120° C. and satisfactorily destroys all organisms
and spores. Material which cannot be subjected to heat may be
sterilized by immersion in antiseptics which arc washed off with
sterile water before use.

ULCERATION

An ulcer is an unhealed area where destruction of the skin or
mucous membrane has occurred. There are many causes of ulcera-
tion and amongst these are burns, overexposure to X-rays and
radium, acute infections of the skin, vascular disorders, deficient
innervation due to spinal or peripheral nerve disease, certain
specific infections such as tuberculosis and syphilis and new growths
(neoplasms).

NEOPLASMS

Neoplasms, new growths or tumours are abnormal masses of
tissue whose growth is unco-ordinated with that of the normal
tissues. They are of two kirlds, the innocent and the malignant.

The innocent tumours usually cease to grow after attaining a certain
size. They push structures aside without invading them and they do
not cause the death of the individual unless they interfere with some

NEOPLASMS

29

vital organ. They can usually be removed surgically with complete
and permanent cure. Examples are papillomas which grow from
epithelium, lipomas from fat, chondromas from cartilage and
osteomas from bone.

The malignant tumours if untreated will spread remorselessly, sap
the patient’s strength and ultimately kill him. Malignant tumours
show none of the tendency to spontaneous cessation of growth which
is a feature of innocent tumours and microscopically they are
characterized by the high proportion of cells undergoing mitotic
division. Malignant epithelial tumours are called carcinomas and
examples are squamous cell carcinoma of the skin and adenocar-
cinomas of various glandular structures. Malignant tumours of con-
nective tissue are sarcomas; those which arise from fibrous tissue are
called fibrosarcomas and those from bone are called osteosarcomas.
Blood forming (haemopoietic), nerve and lymphatic tissue produce
a variety of malignant tumours such as leukaemias, gliomas and
Hodgkin’s disease respectively.

Malignant tumours spread in three different ways, (i) By direct
immion and infiltration of surrounding structures. (2) By lymphatic
spread^ the chief way in which 4 >he carcinomas spread; their cells may
be carried along the lymphatics with the lymph or they may actually
grow along the lymph vessels. The regional lymph nodes are often
affected by secondary growths (metastases) as they filter the lymph,
and malignant cells arrested in them may continue to proliferate.
(3) By the blood stream. Fragments of tumour may enter the veins
draining the area in which the tumour is growing; they arc carried
in the blood stream and arc likely to be held up in the next capillary
vessels they meet. In the case of intestinal growths these will be the
capillaries of the portal circulation in the liver, and hepatic meta-
stases commonly occur in stomach and large bowel cancers. Venous
blood from the kidneys, breasts and limbs will pass through the right
side of the heart and the first capillaries that may arrest malignant
cells will be in the lungs, so that pulmonary metastases may arise.
Blood stream spread is usually a late feature of carcinomas but it is
the chief method of dissemination in sarcomas.

Many malignant tumours are amenable to treatment with radio-
therapy, which is often combined with surgery. The reason why
the regional lymph nodes require treatment in the carcinomas will
be appreciated from the foregoing, and in both carcinomas and
sarcomas radiography of the chest is frequently performed to
exclude the presence of blood borne metastases.

5

Bones. The Skeleton. Joints

BONES

BoAes are usually classified according to their shape into long,
short, flat, irregular and sesamoid.

The long bones are found in the limbs and each is composed of a
tubular shaft of compact and spongy bone with a central medullary
cavity and expanded ends; examples are the femur, radius and
metatarsals.

The short bones such as those of the carpus and tarsus combine
strength with compactness and consist of a thin cortical layer
surrounding spongy bone.

The fiat bones may be mainly protective in function, for example,
the vault of the skull, or, like the scapulae they may provide broad
surfaces for muscle attachments. They usually consist of two tables
of compact bone with a layer of spongy bone between.

The irregular bones such as the vertebrae consist of a relatively thin
cortical layer surrounding spongy bone.

The sesamoid bones are found in muscle tendons in the vicinity of
joints. The patella, the fabella and the small bones seen in the
radiograph in the region of the head of the first metatarsal are
examples of such bones.

DESgRIPTIVE TERMS USED IN OSTEOLOGY

Canal or meatus, a tunnel in bone.

Condyle, a smooth rounded projection.

Epicondyle, a projection above a condyle, e.g. the epicondyles of
the humerus.

Facet, a small articular surface.

Foramen (pi. foramina), a hole perforating a bone, e.g. the fora-
mina in the base of the skuIL

Fossa, a depression in a bone, e.g. the olecranon fossa.

Lamina, a thin plate of bone, e.g. the lamina of a vertebra.

30

Frontal bonm

Nasal bono'

Cervical

vertebrae

Acromial

angle

Clavicle

- Scapula
• Sternum

■ Humerus

Radius 4

Ulna-

Forearm

in

Patella Supination

Tarsal

bones

Metatarsal

bones

Phalanges

3 »

Fig. 5. 1 The bony skeleton.

32

THE SKELETON. JOINTS

Meatus^ see canal. (The plural of this word is also meatus but
meatuses is used in this book.)

Process^ a projection from a bone, e.g. the spinous process of a
vertebra. »

Tubercle^ tuberosity and trochanter^ broad rough elevations, e.g. the
greater and lesser trochanters of the femur.

THE SKELETON

The skeleton may be divided into the axial skeleton comprising the
skull, the hyoid, the ribs, the sternum and the vertebral column, and
the appendicular skeleton which consists of the bones of the limb girdles
and limbs.

yThp Functions of the Skeleton

'' ^{i) It provides a framework for the body.

(2) Jt provides attachments for muscles and ligaments.

(3) protects internal organs, thus the ribs protect the lungs, the
vertebrae protect the spinal cord and the skull protects the brain.

(4) ' It contains the bone marrow in which the blood corpuscles
are formed.

(5) It provides a storehouse for calcium.

JOINTS

A joint or articulation occurs where two or more bones meet. The
structure of a joint depends on whether or not it is designed to allow
movement to occur. Joints may be classified as fibrous^ cartilaginous
and synoviaL

nbfoui tissue Pericranium

N I

Fig. 5.2 A suturnal (fibrous) joint.

Fibrous joints are found between bones at junctions at which no
significant movement is allowed to occur. Examples of such joints
are the sutures of the skull, the inferior tibiofibular joints and the
joints between the teeth and the sockets.

Cartilaginous joints allow a slight or very slight amount of move-

JOINTS 33

nieqt and the joint is more complex than the fibrous joint, there
being a fibrocartilaginous plate between the two l)one ends which
are both covered with fibrocartilage. The external surface of the
joint is reinforced by ligaments which connect the bones. Examples
of cartilaginous joints arc the pubic symphysis and those between
the bodies of the vertebrae where the intervertebral discs are
situated.

Synovial joints, with few exceptions, allow a very free range of
movement. All the joints of the extremities with the exception of the
inferior tibiofibular joints are examples of this group. All the
synovial joints are constructed on the same basic plan and it will
help the student in his studies if he bears this in mind.

Capsule
Synovial membrane
Articular cartilage

Fig. 5.3 A typical synovial joint. ^

THE STABILITY OF SYNOVIAL JOINTS

Certain spinal articulations, the' temporomandibular joints and
the joints of the extremities have to combine freedom of movement
with stability ; this is achieved by several factors : ( i ) The shape of the
bones and cartilages forming the joint, e.g. the ball and socket form
of the hip joint. (2) The capsule which is reinforced by accessory
ligaments. In hinge joints such as the knee the ligaments on either
side of the joint are very strong whereas the capsule, though strong,
is lax anteriorly and posteriorly to allow flexion and extension to
occur. (3) Muscular action, the normal tone of strong muscles sur-
rounding joints keeps the bones in normal relationships and relieves
undue strain falling on the capsule and ligaments. Some muscles,

34 BONES. THE SKELETON. JOINTS

e.g. those of the shoulder, actually partly blend with the joint
capsule and so reinforce it.

The student should, in due course, compare the shoulder and hip
joints. The shoulder joint is a non-weight bearing join t^with a much
wider range of movement than the hip joint. Strength of the shoulder
joint has been sacrificed to a certain extent for mobility. The glenoid
fossa is very shallow and is deepened only to a minor extent by the
cartilaginous glenoid labrum whereas the acetabulum is already
deep and is further deepened by the acetabular labrum. The capsule
is not as strong as in the hip and is relatively weak in its inferior part.
Muscular action, particularly of the short muscles connecting the
scapula to the humeral head, is extremely important in preventing
dislocation but these muscles are less powerful than those around
the hip. Nevertheless dislocation of the shoulder is a comnion injury
and is usually a downward and forward dislocation of the head
through the weakest part of the capsule. The hip is very rarely
dislocated and then usually only by a very severe injury.

CHARACTERISTICS OF SYNOVIAL JOINTS

(1) The articular surfaces of the bones arc covered by hyaline
cartilage which constitutes the articular cartilage. The shapes of these
surfaces, in a large measure, determine the movements occurring at
the joints.

(2) The joint is surrounded by a ligamentous capsule of fibrous
tissue.

(3) The capsule is lined by synovial membrane which dots not cover
the articular cartilage but blends with its margins. The membrane
secretes traces of lubricating fluid and also covers certain intra-
articular structures.

(4) The capsule of the joint is strengthened by additional
ligaments which in hinge-joints arc particularly strong medially and
laterally.

(5) Some joints have intra-articular structures^ e.g. the menisci and
cruciate ligaments of the knees.

(6) The joint has a certain range of movement (p. 35).

(7) The joint receives a nerve supply and has vascular connections.

(Note: When describing a particular synovial joint the student should also indicate
important relations of the joint and the main muscles responsible for its movements.)

CLASSIFICATION OF SyNOVIAL JOINTS

The synovial joints are classified according to the type of move-
ment they allow and in the principal varieties which are listed

PATHOLOGICAL CONSIDERATIONS

35

below it will be seen that many of the terms are self-explanatory.
y^) Hinge-joint, In this type of joint, of which the elbow and knee
are examples, movement occurs in one plane about the transverse
axis, of the limb.

Pivot-joint, In these Joints movement (i.e. rotation) occurs
about the longitudinal axis of the limb; examples are the superior
radio-ulnar and the atlanto-axial joints.

(5) Ball-and-socket joint. These have a very wide range of move-
ment; the hip and shoulder are of this variety.

(4) Condyloid and saddle-joints. An example of the former is the
wrist ^nd of the latter the carpometacarpal joint of the thumb. A
variety of movements is possible.

(5^) Plane joint. This- variety allows gliding movement only.
Examples are the joints between the articular facets of the vertebrae
and those between the carpal and tarsal bones.

MOVEMENTS OF SYNOVIAL JOINTS

Gliding movements occur at many joints and are the only move-
ments possible at the carpal and tarsal joints. Flexion is bending at
Ihc joint and extension is^the Opposite movement ^ straightening the
joint. Adduction implies movcipent towards the median plane of the
body, or, in the case of the digits, towards the middle finger or toe;
abduction is the opposite movement, i.e. away from the midline or
middle finger (toe) as the case may be. Circumduction is the movement
at the shoulder or^hip joints when the limb is moved in a circular
fashion, e.g. the arm in overarm bowling. Rotation iS movement
round the longitudinal axis and is illustrated by the movement of
the arm when the forearm is moved from side to side with the elbow
Hexed to a right angle.

Pathological Considerations

An interruption in continuity of a bone is called 3 . fracture (i.e. a
break). In childhood incomplete or greenstick fractures may occur
and, as their name suggests, they bear a resemblance to incompletely
broken stalks. A compound fracture is one in which the break in the
bone communicates with the surface of the body through a wound
in the overlying skin and soft tissues; it is very liable to infection. A
fracture associated with other injuries such as a puncture of the
pleura or rupture of the spleen by a broken rib is called a com-
plicated fracture and one in which the bone is shattered into several
fragments is said to be comminuted.

36 BONES. THE SKELETON. JOINTS

An epiphysis may slip (i.e. become displaced) as a result of an
injury and after reduction it may fuse prematurely with the shaft
leading to interference in growth in length of the bone.

A dislocation is an abnormal displacement of the bones taking
part in the formation of a joint. Such a condition may be congenital,
for example a child may be born with dislocation of one or both
hips; it may be pathological as a result of ligamentous softening or
destruction by disease or it may be the result of injury, when it is
said to be traumatic.

Osteitis is a bacterial infection of bone and it may be acute or
chronic. If the latter the bone may become very dense and suitable
adjustment of technical factors is likely to be required before
satisfactory radiographs can be obtained.

Arthritis is inflammation of a joint but the term also includes
degenerative conditions such as osteoarthritis. Rheumatoid arthritis
is an intractabl,e inflammatory condition affecting many joints,
especially the small ones of,thc hands and feet. Ankylosing spondy-
litis somewhat resembles rheumatoid arthritis but it involves the
sacro-iliac joints and the spine and leads to fixation of the vertebral
column and thorax. During the painful stages of this condition
radiotherapy may be required to relieve symptoms.

Tumours of bone may be innocent or malignant. The latter may
be either primary, for example, osteogenic sarcoma^ or metastatic from
such primary growths as carcinoma of the breast or prostate.

The Healing of Fractures

During the first few days after a bone has been fractured a blood
clot fills the gap at the site of the injury. The clot is then invaded by
connective tissue and newly formed blood capillaries and is then
called callus. Within a week islands of new bone appear and these
enlarge and coalesce until the fracture is eventually united by bone
which lacks the normal architecture of lamellae, Haversian canals,
etc. This woven bone, as it is called, is gradually replaced by
lamellar (mature) bone. The fracture is usually united sufficiently
soundly for careful use of the part at the stage of union by woven
bone.

Various factors influence the rate of repair of fractures, union
being fastest in the infant. Certain bones such as the scaphoid and
lower one-third of the tibia often take a very long time to unite; this
is probably due to impairment of the blood supply of one fragment.
Failure to secure adequate immobilization may also delay union.

6

The Bones and Joints of the Skull. The
Hyoid

THE SKULL

The skull consists of the cranium and the facial bones.

THE CRANIUM

The cranium is a bony box containing tJie brain and its mem-
branes. It is made up of eight bones, the frontal, occipital, sphenoidal,
ethmoidal and the paired temporal and parietal bones, 'rhe bones
of the vault of the skull arc flattened and consist of an inner and an

37

THE SKULL

-38

outer table between which is a marrow- filled layer known as the
diploe. The lower surface of the cranium is called the base of the skull.

The frontal bone forms the forehead and most of thfe roof of
each orbit. From the supraorbital margin a thin plate ^tends back
into each orbit forming its roof. The two tables are separated above
the nose and inner parts of the orbits by a pair of irregular shaped
cavities, the frontal air sinuses, containing air and communicating
with the nose.

The parietal bones form the sides and roof of the cranium and
each has four borders where articulation with neighbouring bones
occurs at the sutures. Certain important vascular markings are

Zygomatic
Malar Bone

Zygomatic

Arch

Infraorbital

Foramen

Mastoid Process

External Auditory
Meatus

Styloid Process

Mental Foramen

Fig. 6.2 Lateral aspect of the skull.

visible on the inner surface of the parietal bones and they arc often
clearly seen in radiographs; these are the grooves for the anterior
and posterior branches of the middle meningeal artery.

The temporal bones form the lower parts of the sides and part
of the base of the skull. They are frequently studied radiographically
because of the important structures they contain, e.g. the ear, the
mastoid air cells and the auditory nerve. Each bone consists of five
parts, the squamous, petrous, mastoid and tympanic portions and
the styloid process.

The squamous part is a thin sheet of bone which takes part in the

THE SKULL

39

formation -of the side of the cranium. From its lower part the
zygomatic process projects forwards to join a process from the malar
bone to form the zygomatic arch. Below the root of the zygomatic
process is the mandibular. fossa which articulates with the mandible
forming the mandibular joint and behind this lies the external auditory
meatus.

The mastoid part is the most posterior portion of the bone and the
inastoid process projects downwards from it. In this process are the
mastoid air cells; these are epithelium lined Cavities which com-
municate with the tympanic [or mastoid) antrum; a larger space whose
epithelial lining is continuous with the lining of the middle ear.

Articulates with

Fig. 6.3 Internal aspect of the left temporal bone.

Infection reaching the middle ear from the pharynx by way of the
auditory tube (p. 145) may spread to the mastoid air cells.

I'he tympanic part lies in front of the mastoid process and forms the
floor of the external auditory meatus. The styloid process projects
downwards and forwards from the under surface of this part of the
bone.

The petrous part of the temporal bone is an important component
of the base of the skull where it is wedged in between the sphenoidal
and occipital bones. The organs of hearing and equilibrium lie
within it and passing medially from the internal ear is a canal about
i inch (i centimetre) in length, the internal auditory meatus^ which
transmits the auditory and facial nerves.

40

THE SKULL

Fig. 6.4 Under surface of the left temporal bone.

The occipital bone forms the posterior part of the cranium. It is
pierced by the foramen magnum through which the spinal cord passes
from the brain. On each side anterolateral to this foramen are the

Highest curved (nuchal)
line

External occipital protuberance

Inferior curved
(nuchal) line

Base of occipital bone

External

occipital

crest

Posterior

condylar

foramen

Condyle

Jugular

process

Fig. 6.5 Outer surface of the occipital bone.

THE SKULL

4 *

occipital condyles for articulation with the atlas (first cervical vertebra).
The flattened portion behind the foramen magnum is called the
squamous part and in front of the foramen is the basilar portion of the
occipital bone which fuses anteriorly with the sphenoidal bone.

The sphenoidal bone is situated at the base of the skull. It is said
to resemble a bat in flight and it consists of a central body from which
project laterally on each side a greater and a lesser wing.

The body is hollowed out by the large sphenoidal air sinus and its
upper surface bears a deep depression known as the sella turcica
(lit. Turkish saddle) in which the pituitary gland (or hypophysis)
lies. The sella turcica is bounded anteriorly by the optic groove^ at

Superior orbital fissure
Lesser wing —

Articulation of greater
wing with frontal bone

Lateral

Medial

Articulation

pterygoid

pterygoid

with

plate

plate

occipital bone

Sella turcici

Ant. clinoid
process
Foramen
rotundum

Carotid groove

Foramen ovale

Fig. 6.6 Sphenoidal bone, viewed from above.

the lateral ends of which are the optic foramina through which the
optic nerves pass. The posterior boundary of the sella turcica is
formed by a plate of bone, the dorsum sellae, from which project the
posterior clinoid processes. During the first two decades the posterior
surface of the sphenoidal bone is joined to the basal part of the
occipital bone by a plate of cartilage and this junction is often
visible in radiographs (the spheno-occipital suture).

Each greater wing of the sphenoidal bone extends laterally form-
ing the anterior part of^the middle cranial fossa and part of the side
wall of the cranium between the frontal bone and the squamous

D

42

THE SKULL

portion of the temporal bone. There are several foramina in the
greater wing through which important nerves and blood vessels
pass (see p. 43).

The lesser wings are short, pointed and triangular 2fhd project
laterally from the upper and anterior part of the body of the bone.
Both greater and lesser wings take part in the formation of the roof
and outer wall of the orbit and between the two wings is a gap
known as the superior orbital fissure through which nerves and blood
vessels pass to the muscles of the eye, etc. The anterior clinoid processes
project from the posterior surface of tlie medial ends of the lesser
wings and the optic canals perforate the base of each lesser wing.

Fig. 6.7 Diagrammatic coronal section through the facial part of tlic skull to show
the essential construction of the bony nasal cavity anti its relation to adjacent
structures.

These canals lead directly from the optic foramina to the orbits;
each is from 4 to 8 mm. in length and about 4 mm. in diameter.
They are directed forward and outwards making an angle of about
30° with the sagittal plane and they are of great radiographic im-
portance.

The ethmoidal bone is a light spongy structure consisting of
four parts, a horizontal perforated plate called the cribriform plate,
a perpendicular plate and two labyrinths or lateral masses.

The cribriform plate forms the medial portion of the floor of the
anterior cranial fossa and has projecting upwards a crest, the crista
gain. The perpendicular plate projects downwards approximately in
the sagittal plane forming part of the nasal septum. The labyrinths^

THE SKULL

43

in which are situated the ethmoidal air cells, project down from the
cribriform plate on each side and form part of the lateral wall of the
nose.

THE CRANIAL FOSSAE

If the skull-cap and the brain and its membranes arc removed the
interior of the base of the skull can be studied. It is usual to describe
three cranial fossae: an anterior, a middle and a posterior.

Crista Calli

Ant. Clinoid
Process

(Foramen

Rotundum)

Foramen

Ovale

Foramen

Lacerum

Internal

Auditory

Meatus

Post.Clinold

Process

Grooves
)for
Middle
} Meningeal
Vessels

Petrous part
of Temporal
Bone

Transverse or
Lateral Sinus

Foramen Transverse

Magnum Sinus (Sigmoid

part)

Fig. 6.8 The internal surface of the base of the skull.

( I ) The anterior cranial fossa extends from the front of the base of
the skull to the posterior margin of the lesser wings of the sphenoidal
bone and the anterior margin of the optic groove. The floor is
formed by the orbital plates of the frontal bone, between these by
the cribriform plate of the ethmoidal bone and posteriorly by the
sphenoidal bone. The cribriform plate contains many tiny perfora-
tions by which the olfactory nerves pass from the nose to the interior

44 the skull

of the skull. The anterior cranial fossa contains the frontal lobes of
the brain.

(2) The middle cranial fossa is bounded anteriorly by the posterior
border of the anterior fossa, i.e. the lesser wings of the "Sphenoidal
bone and the anterior margin of the optic groove. The posterior
border of the fossa is formed medially by the dorsum sellae and
laterally by the superior margins of the petrous portions of the
temporal bones. The lateral boundaries consist of the squamous
parts of the temporal bones, the lower parts of the parietal bones and
the lateral parts of the greater wings of the sphenoidal bones. In the
middle of the floor is the sella turcica and on either side arc the
greater wings of the sphenoidal and upper surfaces of the petrous
portions of the temporal bones. Between the greater and lesser
sphenoidal wings are the superior orbital fissures. In the floor of the
middle fossa there are several foramina on jeach side; the most
important of these are the. foramen rotundum and the foramen ovale for
branches of the fifth cranial nerve, the foramen spinosum for the
middle meningeal artery and the foramen lacerum which lies at the
apex of the petrous part of the temporal bone. The foramen laccrum
is occluded by cartilage below but its upp2r part transmits the
internal carotid artery. The groove for the middle meningeal artery
and vein runs forwards and laterally from the foramen spinosum for
about J inch (2 centimetres) where it divides into an anterior ard a
posterior branch. The middle fossa contains the temporal lobes of the
brain and, within the sella turcica, the pituitary gland.

(3) The posterior cranial fossa is bounded anteriorly by the petrous
parts of the temporal bones and near the midlinc by the dorsum
sellae of the sphenoidal bone. Posteriorly the fossa is limited on
either side by the transverse sulcus on the squamous portion of the
occipital bone. An aperture in its floor, the for amen magnum, transmits
the spinal cord and closely related to this arc the two jugular foramina
through which the internal jugular veins leave the skull. The open-
ings of the internal auditory meatuses or canals which transmit the
auditory and facial nerves will be seen in the posterior aspect of each
petrous portion of the temporal bones. The parts of the brain known
as the cerebellum, the pons and the medulla lie in the posterior
cranial fossa.

THE CRANIAL SUTURES

Fibrous joints, known as sutures, unite the bones of the skull. These
joints permit a certain amount of moulding to occur during birth;

THE SKULL

45

some are obliterated during growth but many persist throughout
adult life and are visible in radiographs. Small bones, called
Wormian bones, are often found in the sutures.

The main sutures are (i) the sagittal between the two parietal
bones, (2) the coronal between the frontal bone and the anterior
borders of the parietal bones, (3) the squamosal between the
squamous part of the temporal bone and the inferior border of the
parietal bone on each side and (4) the larnbdoid between the occipital
l;one and the posterior borders of the parietal bones.

At birth the bones of the skull are incompletely ossified and there
are gaps between them which are filled in by membrane. These gaps

are called fontanelles and the largest arc found at the two ends of
the sagittal suture. The anterior fontanelle is at the junction of
the frontal with the two parietal bones and the posterior is at the
junction of the occipital with the parietal bones. The anterior fonta-
nelle closes by about 18 months of age and the posterior by about 6
months.

THE FACIAL BONES

The bones of the face consist of the two upper jaws or maxillae,
the two cheek or malar bones, the two nasal bones, the mandible or
lower jaw and others which take part in the formation of the medial
wall of the orbit, the nasal septum and the hard palate.

THE SKULL

46

The maxillae or upper jaws contribute to the formation of the
floors of the orbits, the lateral walls of the nose and the roof of the
mouth. The teeth arise from the alveolar processes and a large cavity,
the maxillary sinus or antrum occupies the body of each ma?cilla.

The mandible or lower Jaw consists of a horizontal portion, the
body^ and two ascending rami (sing, ramus) which are bony plates
projecting upwards from the ends of the body. The middle of the
body is called the symphysis and from the upper end of each ramus
two processes project, these are the pointed coronoid process anteriorly
and the rounded condyle or head posteriorly which takes part in the
formation of the mandibular Joint. A canal known as the mandibular

Maxillary
Antrum of
Highmore

Hard

Palate

Alveolar

Process

Fig. 6.10 The left maxilla, medial aspect.

or alveolar canal traverses much of the ramus and adjacent part of the
body on each side; it carries nerves and vessels to the teeth of the
lower Jaws and ends anteriorly at the mental foramen.

The mandibular or temporomandibular joint is a synovial
Joint between the articular tubercle and mandibular fossa of the
temporal bone above and the condyle of the mandible below.
There is an articular disc within the Joint which divides it into an
upper and a lower cavity. Articular cartilage covers the Joint surfaces
and there are synovial membrane, a Joint capsule and ligaments.
The movements of the Joint allow the mandible to be raised and
lowered, to be carried forwards or backwards and to be moved

THE SKULL

47

somewhat from side to side. When the mouth is opened, i.c. the
mandible is lowered, the condyles and the articular disc move
forwards out of the mandibular fossa on to the articular tubercles,
the bony prominences in front of the fossae.

Immediately posterior to the mandibular fossae are the external
auditory meatuses and this close relationship is of clinical importance.

'rhe orbits arc pyramidal cavities which contain the eyes, the
occular muscles, the optic nerves and the lacryinal (tear) glands,
rheir long axes diverge as they are traced forwards and each orbit
has a roof, a floor and medial and lateral walls.

Coronoid process

Oblique line Mental foramen

Mental

tuberosity

().ii 'I'lic mandible. The right half viewed from the lateral side.
(For Base read Body)

The roof consists of the orbital plate of the frontal bone and the
lesser wing of the sphenoidal bone. I’lic floor is formed by the upper
surface of the maxilla, lire medial wall is made up of several bones,
including the lateral aspect of the labyrinth of the ethmoidal bone ;
the optic foramen lies posteriorly in this wall. The lateral wall
consists of the malar bone anteriorly and the greater wing of the
sphenoidal bone posteriorly. The posterior parts of the roof and
lateral wall are separated by the superior orbital fissure and between
the lateral wall and floor is the inferior orbital fissure.

The nose is the organ of smell and is divided into the external nose^
a bony and cartilagfnous stnicture which bears the nostrils or

THE SKULL

48'

anterior nares, and the nasal cavity which opens posteriorly into the
nasopharynx through the posterior nares. A septum which lies
approximately in the midline divides the nasal cavity into right and
left halves.

The nasal cavity has a roof consisting of the cribriform plate of
the ethmoidal bone (see Fig. 6.7), a floor formed by the hard
palate, and lateral walls which consist principally of the medial
surfaces of the maxillae below and the medial surfaces of the
ethmoidal labyrinths above. These lateral walls are largely obscured

Superior

Orbital

Fissure

Small Wmg
of Sphenoid

Great Wing
of Sphenoid

Inferior

Orbital

Fissure

Infra-orbital

Canal

Fig. 6.12 Boundaries of the right orbit viewed from in front.

by the conchae or turbinate bones which project downwards and medi-
ally and to some extent warm and filter the incoming air. Beneath
each concha is a passage called a meatus.

The inferior concha is a separate bone articulating with the nasal
surface of the maxilla; beneath it is the inferior meatus into which
opens the nasolacrymal duct, a bony canal connecting the orbit with
the nasal cavity down which tears, the secretion of the lacrymal
glands, may pass.

The middle concha projects from the nasal surface of the ethmoidal
labyrinth and below it, into the middle meatus, open the maxillary
antrum, the frontal sinus and the anterior and middle ethmoidal
sinuses.

The superior concha also projects from the nasal surface of the

THE SKULL

49

elbmoidal labyrinth and immediately below it is the superior meatus,
into which the posterior ethmoidal sinus opens. Behind this is the
spheno-cthmoidal recess with which the sphenoidal air sinuses
communicate.

The accessory nasal sinuses are cavities in the bones in the
neighbourhood of the nasal passages with which they communicate ;
they are lined by ciliated mucous membrane. They develop as out-
pouchings from the nasal passages and are sufficiently well developed
to be demonstrable in radiographs at 4 or 5 years of age.

They may be considered as anterior and posterior groups', the former
open into the middle meatus of the nose and the latter into the

Superior
meal us
Bulla elhiuoid-
aiia

Vestibulo

Oriflec of naso-
lacrimal duct
Inferior
meatus

Orifice of
sphenoidal
air sinus
Superior
concha

Sphenoidal
air sinus
Middle
concha

Pharynffo-

tympanic

lube

JMg. (i.13 riic laU-ral wall of the right half of the nasal cavity, as seen after
removal of the greater part of the conchac (after Sabotla).

superior meatus and into the sphcno-cthmoidal recess. The anterior
group consists of the two maxillary antra, the two frontal sinuses and
the two anterior and middle ethmoidal sinuses. 'I'he posterior group
comprise the two posterior ethmoidal sinuses and the two sphenoidal
sinuses.

The frontal sinuses are situated one on each side of the midline and
lie between the inner and outer tables of the frontal bone over the
root of the nose and inner parts of the orbits. They vary considerably
in size and are separated from each other by a bony septum. They
drain into the middle meatus of the nose.

The maxillary sinuses (or antra) are two large cavities, one in each
upper jaw. Each is roofed by the orbital surface of the maxilla and

50 .

THE SKULL

Frontal air sinus

Frontal bone

Zygomatic
bone

Part of

sphenoidal

bone

Zygomatic
arch

Mandibit

Maxillary
air sinus

Fig. 6.14 (a) Radiograph showing the accessory nasal sinuses;

(b) Line drawing of (a).

The ethmoidal and sphenoidal sinuses are not shown in this diagram.

THE SKULL

its floor is formed by the alveolar process of the maxilla from which
the roots of the molar and premolar teeth may project into the
sinus. The medial wall forms part of the lateral wall of the nose and
is perforated by the aperture which connects the antrum to the
middle meatus. The anterior and posterior walls of the maxillary
sinus are the inner aspects of the facial and posterior surfaces of the
maxilla respectively.

The ethmoidal sinuses arc situated in the labyrinths of the ethmoidal
Mental tuberosity Genial tubercle

bones and so arc placed between the nasal passages and the orbits.
They consist of a number of thin-walled bony cavities or cells lined
with mucous membrane which are arranged in anterior, middle
and posterior groups. The anterior and middle ethmoidal cells drain,
like the frontal sinuses, into the middle meatus of the nose and the
posterior cells drain directly into the superior meatus.

The two sphenoidal sinuses occupy the body of the sphenoidal bone
and are separated from each other by a thin bony septum. The sella
turcica is above them and they communicate with the nasopharynx
by apertures in their anterior walls.

5-2

THE HYOID

THE HYOID

The hyoid is a small bone lying in the anterior pari of the neck
between the mandible and the larynx. It consists of a body, two
greater and two lesser cornua. It is suspended from the styloid
processes of the temporal bones by the stylohyoid ligaments and
gives origin to the muscles of the tongue.

RADIOGRAPHIC APPEARANCES OF THE SKULL

THE ANTERIOR RADIOGRAPH

The diploic structure of the skull is visible in this radiograph and
the sagittal, coronal and lambdoid sutures may be seen. 'I’he frontal

Sagittal suture
Coronal suture
Mastoid process

Frontal sinus

Upper margin
of orbit

Internal

auditory

meatus

Nasal septum

Atlanto-
occipital loint

Lower margin
of orbit

Inferior

conche

Styloid process
of

temporal bone
Mandible

Mental foramen

Fig. 6.16 Radiograph of skull in the anterior projection.

sinuses and the orbits produce characteristic appearances and., unless
the ray is directed towards the feet, the petrous portions of the
temporal bones are superimposed on the lower halves of the orbits.

RADIOGRAPHIC APPEARANCES OF THE SKULL

53

Posterior dinoid process

Anterior clinoid processes

Frontal bone “

Anterior br of middle
meningeal artery

Frontal air sinus

Floor of anterior
fossa .

Greater wing of
sphenoidal bone

Sphenoidal ai
sinus

Condyle of
mandible

Fig. 6.17 (d) Radiograph of skull,
(of no pathological significance),
radiograph of skull. The markings

External auditory
meatus

Coronal suture
Diploic vessels
^ Parietal bone

Sguarnosal
suture

Posterior br. of
middle

meningeal artery

Lambdoid suture

Squamous part
of occipital bone

Transverse sinus

^Petrous part of
temporal bone

Mastoid air cells

Lateral projection. Note calcified pineal body
(b) Line drawing of structures seen in lateral
on one side only arc shown.

THE SKULL

54

In the upper parts of the orbital shadows the lesser wings of the
sphenoidal bones are seen and the ethmoidal and sphenoidal air
sinuses and the nasal cavity produce a composite shadow. On
either side of the nose are the maxillary sinuses and projecting into
the nasal cavity from its lateral walls are the conchae. •

THE LATERAL RADIOGRAPH

In this radiograph the attention is usually directed to the bones of
the vault and the bones of the base. 'Fhe facial bones arc superim-
posed on each other and arc not usually the object of special study
in this projection.

The vault varies in thickness; the squamous parts of the temporal
and occipital bones arc usually thinner and therefore more trans-
radiant than the .parietal and frontal bones which, because of their
greater opacity, appear whiter in the radiograph. Where the ray
strikes the vault tangentially the two tables and the intervening
diploe may be apparent. The coronal, squamosal and lambdoid
sutures will be demonstrated but the sagittal, of course, v^^ll not
be seen.

Certain markings will be visible in the vaults; the convolution of
the brain may produce ^digital markings^ which arc depressions on
the inner table and are often seen in children. Several markings
caused by blood vessels may be seen and these are listed below.

Vascular markings shown in the radiograph of the vault of the skull:

(1) the anterior branches of the middle meningeal vessels arc
responsible for the grooves which cross the squamous parts of the
temporal bones and the posterior branches may be seen running
backwards across the parietal bones at a lower level.

(2) The groove for the transverse sinus, a large vein within the
skull, may appear as a transverse band J inch (i centimetre) in width
crossing the occipital bone.

(3) Certain veins run in the diploic space and may be seen as
branching dark lines which arc usually most marked in the parietal
bones.

(4) The arachnoid granulations (see Chapter 17) may produce
small indentations of the inner table of the skull, usually on cither
side of the midline.

Other structures which may be seen superimposed on the vault of
the skull include:

RADIOGRAPHIC APPEARANCES OF THE SKULL 55

(1) The pinna of the ear, which may produce an arc-like shadow
above the petrous portions of the temporal bones.

(2) The pineal body, a single midline structure in the brain
(p. 240), which may become calcified and will then be visible in the
radiograph as a shadow about ^ inch (2 millimetres) in diameter,
approximately i inch (2.5 centimetres) above and ^ inch (i centi-
metre) behind the external auditory meatus.

Fig. 6.18 (a) Radiograph of the skull in the superior (SMV) projeclion.

(3) The posterior parts of the choroid plexuses of the lateral
ventricles (p. 244, Chapter 17) frequently calcify and then show as a

THE SKULL

56

shadow or pair of shadows about J inch (2 centimetres) behind the
site at which the pineal body will be seen if calcified.

The base of the skull is seen in profile in this projection. Anteriorly
the frontal sinuses expand the diploic space at the base of the frontal
bone; behind them the orbital plates of the frontal boneS, which
roof in the orbits, are continuous with the lesser wings of the sphenoi-
dal bones, from which the anterior clinoid processes project. The
cribriform plate of the ethmoidal bone may be identified below the
orbital plates of the frontal bones.

Lateral wall ot
maxillary sinui

Greater wing of
sphenoidal bone

Coronoid process
of mandible

Condyle of
mandible

Petrous apex

y

External auditory
meatus

Mastoid air cells

Superimposed hyoid
bone, anterior arch of
atlas and anterior margin
of foramen magnum

Nasal septum
Orbit

Maxillary sinus

Body of mandible

Sphenoidal air sinus

- Foramen ovale

' Foramen spinosum

Foramen lacerum

Internal auditory
meatus

Jugular foramen

Odontoid process
of axis

Foramen magnum

Cervical spine

Fig. 6.18 (b) Line drawing of structures seen in the radiograph taken in this
projection.

The floor of the middle fossa in its anterior portion, where it is
formed by the greater wings of the sphenoidal bones, produces
curved white lines (or a single line if the two sides are superimposed)
parallel with the floor of the sphenoidal sinus as it arches upwards
to the lower part of the coronal suture of each side.

The sella turcica (pituitary or hypophyseal fossa) is seen as a
round or oval depression above the sphenoidal air sinus; above it

RADIOGRAPHIC APPEARANCES OF THE SKULL 57

in front are the anterior clinoid processes and behind are the
|)osterior clinoid processes and dorsum sellae.

Between the middle and posterior cranial fossae is a dense white
triangular shadow caused by the superimposition of the two petrous
parts of the temporal bones. A transradiant area in this shadow is
caused by the external auditory meatus and behind this the mastoid
air cells will be seen as an area of variable size, honeycombed with
transradiancies. In front of the external auditory meatus the mandi-
bular joint is shown.

THE SUPERIOR (SUBMENTOVERTICAL) RADIOGRAPH

Anteriorly the facial bones and the maxillary sinuses are super-
imposed upon the anterior cranial fossa. The lesser wings of the
sphenoidal bones separating the anterior from the middle cranial
fossa are seen as two curved lines convex forwards. In the floor of
the middle fossa, on each side, the foramina lacerum, ovale and
spinosum will be identified. The petrous portions of the temporal
bones intervene between the middle and posterior fossae and the
shadows of the atlas vertebra and odontoid process of the axis are
superimposed on the foradien magnum.

7

The Bones and Joints of the Vertebral
Column and Thorax

THE VERTEBRAL COLUMJV

The vertebral column is the central axis of the body and consists
of irregular bones called vertebrae. It protects the spinal cord, and
supports the weight of the head and trunk which it transmits to the
lower limbs.

The vertebrae, with certain exceptions, are separate bones bound
to each other by ligaments and capable of a certain amount of
movement because of the intervening joints. They are grouped
according to the region in which they lie as seven cervical^ twelve
thoracicy five lumbar, five sacral, and four coccygeal. Although there is
considerable variation in the appearance of the vertebrae in the
different regions4they are all built up from the s^me basic plan, but
the first two cervical and the sacral and coccygeal vertebrae show a
greater departure from this plan than do those of the other regions.

Essentially a typical vertebra consists of a rounded body anteriorly
with flattened upper and lower surfaces and a vertebral arch poster-
iorly; these enclose a space through which runs the spinal cord, it is
known as the vertebral or spinal foramen or the neural canal.

The vertebral or neural arch consists of a pair of pedicles which
constitute the sides of the arch and a pair of laminae which roof
in the arch posteriorly. Seven processes spring from the arch; in
the midline projecting from the junction of the two laminae is the
spinous process', arising from the junctions of the pedicles with the
laminae on each side are the transverse processes, and directed upwards
and downwards , respectively are the superior and inferior articular
processes on which are the facets for the posterior intervertebral
articulations. Intervening between the upper and lower surfaces of
adjacent vertebral bodies are the intervertebral discs', the gaps between
the pedicles and neighbouring vertebrae are called the intervertebral
foramina and the spinal nerves and vessels pass through them.

58

THE VERTEBRAL COLUMN

59

THE CERVICAL VERTEBRAE

" The seven cervical vertebrae differ somewhat from the basic plan
and this departure is most extreme in the first two. The first cervical-
vertebra is called the atlas and it has an anterior arch in place of a body.
The second, called the axis^ has projecting upwards from its body a
stout peg, the odontoid process.

Fig. 7.1 The vertebral column.

Lateral aspect of the vertebral column showing normal curves.
Nole\ The cervical and lumbar regions show a slight forward
convexity and the thoracic and sacral regions show a backward
convexity.

The chief characteristics of the cervical vertebrae are: (i) the
bodies are relatively small, oval in shape and broadest from side
to side; (2) the neural arches are large; (3) the transverse

6o

THE VERTEBRAL COLUMN

Fig. 7.2 A thoracic vertebra — superior aspect.

■Superior articuiar process

Intervertebraf

foramen

Articular facets
for head of
sixth rib

Inferior

articular

processes

Facet for
tubercle of
Sixth rib

Spinous

process

Fig. 7.3 Articulated thoracic vertebrae — lateral aspect.

THE VERTEBRAL COLUMN

6l

Pedicle

Anterior tubercle

Foramen

transversarium

Groove for cervical
nerve

Posterior tubercle

Articular process

Lamina

Spinous process

P'l'g. 7.4 A typical cervical vertebra.

processes arc perforated from al)ovc downwards by a foramen (the
foramen transversarium) through which the vertebral artery runs on its
way to enter the skull; (4)' the spinous processes of the first six verte-
brae are bifid (divided) at the tips but that of the seventh is not so
divided, it is the most prominent cervical spinous process and, as it
produces a visible prominence on the back of the neck, the seventh
cervical vertebra is called the vertebra promincm.

Posterior tubercle

Fig. 7.5 The atlas — .superior aspect.

62

Odontoid

process

THE VERTEBRAL COLUMN

Foramen

transversarium

Groove for transverse
ligament

Facet for aFlas

Fig. 7.6 The axis- posterosuperior aspect.

THE THORACIC VERTEBRAE

The twelve thoracic vertebrae increase in size from above dow'ii-
wards and show the following characteristics: (i) the bodies are
heart-shaped and on either side they bear facets for articulation with
the heads of the ribs; (2) the neural arches are relatively small;
(3) the spinous processes are long and downwardly directed ; (4) the
transverse processes are conspicuous and articulate (in the case of
the upper ten) with tubercles on the ribs (see Figs. 7.2, 7.3).

THE LUMBAR VERTEBRAE

The five lumbar vertebrae show the following features: (i) the
bodies are large and wide; (2) the vertebral foramina are triangular

Slip, articular

process Transverse process

Lamina

Inf. articular process

Fig. 7.7, A typical lumbar vertebra — lateral aspect.

THE VERTEBRAL COLUMN

63

in shape and are larger than in the thoracic region; (3) the spines
are quadrangular and project directly backwards; (4) the superior
articular processes have projecting backwards from them the
mamillary processes.

The lumbar vertebrae, of course, have no facets for articulation
with the ribs.

THE SACRUM

The sacrum is triangular in shape and consists of five vertebrae
fused into one bone. Its apex is directed downwards and articulates
with the coccyx; its base, directed upwards, articulates with the
lumbar spine at the lumbosacral junction. The pelvic surface is
directed forwards and is perforated by the anterior sacral foramina,
the dorsal surface is directed backwards and is perforated by the

posterior sacral foramina. The sacral nerves pass through these
foramina as they leave the spinal canal. The lateral surface bears in
its upper part an articular surface which articulates with the ilium
at the sacro-iliac joint. The vertebral arches of the sacral vertebrae
are fused into one sacral canal and the anterior and posterior
sacral foramina communicate with the canal.

THE COCCYX

The coccyx is a small triangular bone composed of four rudimen-
tary vertebrae; the lower three are usually fused together and the

THE vertb:bral column

64

first piece is generally separate. The apex of the coccyx points down-
wards and forwards and the base articulates with the sacrum.

THE SPINAL CURVES

When viewed from in front or behind the spine is straight bui
when seen from the side it presents a series of curves. In the foetus
there is one primary curve with its convexity backwardly directed from
the cervical to the sacral region. When the child can sit upright a
secondary ciirvcy convex forwards, develops in the cervical region and
when he can stand a similar curve develops in the lumbar region.

The adult vertebral column shows (see Fig. 7.1) forward con-
vexity of the cervical and lumbar regions and backward convexity
of the thoracic and sacral regions.

JOINTS OF THE VERTEBRAL COLUMN

The majority of the vertebrae articulate with each other through
cartilaginous joints, the inlerverlebral disesy between their bodies and

Hy»line

cartilage

Anterior

longitudinal

ligament

Disc

Intervertebral

foramen

Splnoui

process

I^ig- 7-9 Sagittal section of part of the
vertebral column showing ligaments and
intervertebral discs.

by a series of synovial joints between the articular facets on the
vertebral arches. The vertebral bodies are joined also by the anterior
and posterior longitudinal ligaments which run as continuous bands
down their anterior and posterior surfaces.

The intervertebral disc. Each disc consists of an upper and a lower

JOINTS OF THE VERTEBRAL COLUMN 65

cartilaginous plate between which lies the jelly-like nucleus pulposus
which is itself surrounded by a fibrous ring called the annulus
Jihrosus. No discs are found between the first two cervical vertebrae
nor, of course, in the sacrum or coccyx.

The neurocentral joints. In the cervical region there are small
synovial joints in the margins of the intervertebral discs adjoining
the intervertebral foramina; these are called the neurocentral joints.
Degenerative changes in these joints, a condition known as cervical
spondylosis, may be responsible for local and referred pain because the
spinal nerve, as it passes through the intervertebral foramen, may be
damaged by osteophytes (small bony spurs which form at the
periphery of osteoarthritic joints).

The synovial joints between the vertebral arches consist of the
articulations between, the superior and inferior articular facets of
the adjacent vertebrae. These facets are covered with hyaline
cartilage and the joints posse.ss capsular ligaments and synovial
membranes.

Tlie neural arches arc also connected by the jlaval ligaments
(ligarnenla JIava) which join the laminae, the interspinous ligaments
betw'een the spinous processes and the supraspinous ligaments which
run down the tips of the sginous processes. In the cervical region the
supraspinous ligament is greatly strengthened to become the
nuchal ligament (ligamentum nuchae) which extends from the seventh
cervical vertebra to the occiput.

'rhe movements which occur in the vertebral column are flexion,
extension, lateral jiexion, circumduction and rotation. Flexion is forward
movement, extension is backward movement and lateral flexion is
the bending of the body to one or other side. Circumduction is a
combination of these and rotation occurs when the back is twisted;
the latter is most free in the thoracic part of the vertebral column
and absent in the lumbar.

THE ATLANTO-OCCIPITAL JOINT

This synovial joint intervenes between the occipital condyles
which arc found on either side of the foramen magnum above, and
the facets on the superior surfaces of the lateral masses of the atlas
vertebra below. The principal movements are flexion and extension,
as in nodding the head, but a limited degree of lateral flexion of the
head also occurs.

THE ATLANTO-AXIAL JOINT

The synovial joint between the first and second cervical vertebrae

66

THE VERTEBRAL COLUMN

consists of three parts, one between the odontoid process and tlie
anterior arch of the atlas and the other two between the two lateral
masses of the bones. The movement occurring between the bones is
rotation of the atlas (and hence the head) on the axis.

RADIOGRAPHIC APPEARANCPIS OF THE VERTEBRAL COlCjMN

Cervical Region

A posterior view through the open mouth shows the atlanto-
axial articulation with the odontoid process lying between the two
lateral masses of the atlas vertebra.

The lateral projection shows the anterior and posterior arches of
the atlas, the odontoid process projecting upwards from the body
of the axis, the posterior intervertebral articulations and the spinous
processes. The transverse processes arc superimposed on the bodies
in this projection. The anterior and posterior surfaces of the vertebral
bodies and the posterior surface of the spinal canal form smooth and
roughly parallel curves.

Thoracic Region

The posterior radiograph shows the bodies of the vertebrae, with
the spinous processes and laminae superimposed upon them. Each
spinous process is projected on to the vertebra below. The trans-
verse processes project laterally and those of the first thoracic
vertebra are also directed upwards, in contrast to those of the
cervical transverse processes which are directed somewhat down-
wards. The intervertebral disc spaces arc seen with varying degrees
of clarity depending on their relation to the axis of the X-ray beam.
The pedicles produce a characteristic line of white oval rings super-
imposed on each side of the vertebral bodies. The costovertebral and
the costotransverse joints will be seen. The transradiant trachea and
the dense heart shadow will also be projected on to the film.

In the lateral projection the bodies, rectangular in shape, arc seen
to be separated by the intervertebral disc spaces; the pedicles
project posteriorly from the bodies and between them the inter-
vertebral foramina are seen. The ribs, spinous processes and laminae
tend to be superimposed and the upper four thoracic vertebrae are
usually greatly obscured by the shoulder girdles.

Lumbar Region

The posterior view shows the bodies, laminae, spinous processes,
transverse processes and intervertebral disc spaces clearly. The

RADIOGRAPHIC APPEARANCE 67

pedicles produce conspicuous ring-shaped shadows and just above
these the posterior intervertebral joints are seen as narrow slits.
The lateral view demonstrates clearly the bodies, the disc spaces.

Body ( 5 rd L)

Transverse

- ■ ^^^Superior

process r

AV articular

Lamirio ^

/ JJl V ^Pedicle

Inferior ^

articular

\

process

Spinous process

Fifjr, y,jo (a) Radiographic appearances of the lumbosacral
region-- posleriorprojcction; (If) Line drawing of 3rd
lumbar vertebra.

the intervertebral foramina, the intervertebral joints and the
spinous processes.

Oblique views of the lumbosacral junction are sometimes required
for the demonstration of the part of the neural arch between the
superior and inferior articular processes.

68

THE VERTEBRAL COLUMN AND THORAX

Superior articular process

Fig. 7. 1 1 (a) Radiographic appearances of the lumbar spine —
lateral projection; (d) Line drawing of 3rd lumbar vertebra.

Sacrum and Coccyx

The sacrum is seen as a triangular bone with the apex below. It is
made up of two lateral portions or masses and a body between them.
The body is relatively dense as it consists of the fused bodies and

THE VERTEBRAL COLUMN AND THORAX 69

neural arches of the sacral vertebrae. Articulating with the lower
end is the coccyx which also is shaped like an inverted triangle.

Ossification of the Vertebral Column

Each vertebra ossifies from three primary centres, one for the body and
one for each side of the neural arch. At birth a radiograph will show these
separate centres but by the end of the ist year the neural arches will have
fused and by 6 years of age the arches will be joined with the bodies,
failure of closure of the neural arch sometimes occurs especially in the
lumbar region, and it is then called spina bifida. During childhood
secondary ossific centres appear for the tips of the spinous and transverse
processes and a ring-shaped epiphysis appears for the upper and lower
surfaces of each vertebral body. The centre of this ring remains unossified
and persists as the cartilaginous plate which is found in the upper and
lower surfaces of the intervertebral discs.

THE THORACIC CAGE

Hie thoracic cage is a conical structure composed principally of
bones and muscles. The bones consist of the twelve thoracic verte-
brae posteriorly, the sternum anteriorly and the encircling ribs
(p. 62, 70). Between the ribs are the intercostal muscles and
separating the thorax from the abdomen is the diaphragm. The
apex of each half of the thoracic cavity is separated from the neck
by a fascial layer called Sibson’s fascia. I’hc thoracic cage is lined
by pleura (p. 152) and contains the lungs and mediastinum.

The surface markings of the thorax arc dealt with on page 267
el sqq.

THE STERNUM

The sternum forms the middle portion of the anterior wall of the
thorax and consists of three parts, the manubrium^ the body and the
xiphoid process. In early life these parts are represented by circular
centres of ossification which are sometimes visible in slightly oblique
anterior and posterior radiographs.

The manubrium is a triangular bone which articulates with the
clavicles on either side of its upper border and between the articular
surfaces is the suprasternal notch. Below, the manubrium articulates
with the body of the sternum at the sternal angle. The second costal
cartilages lie at this level. The first costal cartilages articulate with
the lateral aspects of the manubrium just below the clavicles.

70

THE STERNUM AND RIBS

The body of the sternum is long and narrow and articulates in
conjunction with the manubrium with the second costal cartilages.
Below these it articulates with the third, fourth, fifth, sixth and
seventh costal cartilages on each side.

The xiphoid process is the smallest and lowest piece of the sternum;
it may be cartilaginous or bony.

Xiphoid process

Fig. 7.12 The sternum and costal cartilages. The numbers arc
the serial numbers of the costal cartilages.

THE RIBS

There are usually twelve ribs on each side. All articulate poster-
iorly with the vertebral column and arch obliquely round the
thorax to be connected, in the case of the upper seven ribs, through

THE RIBS

71

the costal cartilages to the sternum. The eighth, ninth and tenth have
cartilages which are attached to each other and join the seventh
costal cartilage. The eleventh and twelfth ribs are called floating
ribs since their anterior ends are free.

The anterior end of each rib is expanded and the posterior end
possesses a head^ a neck and a tubercle \ these will be considered in
connection with the costovertebral joints. Between the ribs are the
intercostal spaces which are occupied by the intercostal muscles,
nerves and blood vessels.

Sometimes cervical ribs are met with. They arise from the seventh
cervical vertebra and may join the first thoracic rib, the first costal

for costa/ cartilage

cartilage or the sternum. They are of importance as they may
cause nervous and vascular symptoms in the upper limbs.

72 THE VERTEBRAL COLUMN AND THORAX

JOINTS OF THE THORAX

THE MANUBRIOSTERNAL JOINT

The articulation between the manubrium and the body of the
sternum is a cartilaginous joint so the two bones are connected by a
plate of fibrocartilage. There is a restricted degree of movement at
the joint during breathing.

THE STERNOCOSTAL ARTICULATIONS

Synovial joints exist between the body of the sternum and the
second to the seventh costal cartilages of each side.

THE COSTOVERTEBRAL JOINTS

Each rib articulates with the vertebral column by two synovial
joints, one between the head of the rib and the-facct on the side of
the appropriate thoracic vertebra and the other between the tubercle
and neck of the rib and the transverse process of the vertebra.
Elevation of the ribs occurs at these joints during breathing, thus
helping to draw air into the lungs.

Fig. 7.14 Diagram to show, from above, the costovertebral articul-
ations. On the left side the costovertebral ligaments and joint capsules
have been removed.

Pathological considerations

The vertebral column may show abnormal curves for a variety of

JOINTS OF THE THORAX

73

reasons and these are termed: kyphosis^ a posterior convexity (‘round
^boulders’), lordosis is the opposite, an exaggerated anterior con-
vexity (as normally occurs in late pregnancy), scoliosis is a lateral
curvature (e.g. following infantile paralysis or, more commonly, of
unknown causation ‘idiopathic scoliosis’).

A crippling condition known as ankylosing spondylitis results in
fusion of the vertebral and sacro-iliac joints. This disease is some-
times grouped as one of the rheumatoid diseases.

Spondylolisthesis is the term used to describe the forward slipping
of a vertebra (usually of the lower lumbar region) on the vertebra
below as a result of a defect in the neural arch.

Slipped or prolapsed intervertebral disc is a common cause of backache,
sciatica, etc. It results from a rupture of the annulus fibrosus of the
disc, usually by a forcible flexion movement (e.g. lifting a weight) so
that the semi-fluid nucleus pulposus is extruded posteriorly or pos-
terolaterally. The extruded nucleus may compress the spinal cord
or a nerve root.

Vertebrae arc frequently the site of metastatic cancer.

Radiography of the vertebral bodies provides a useful way of
studying bone changes in various developmental abnormalities and
metabolic disturbances, o

8

The Bones and Joints of the Appendicular
Skeleton

BONES AND JOINTS OF THE UPPER LIMB

THE CLAVICLE

The clavicle or collar bone runs horizontally at the root of the
neck and transriits part of the weight of the, upper limb to the
trunk. The shaft is iS-shaped and its medial half is convex forwards.
The medial end is roughly square and articulates with the sternum,

Lower Aspect

Fig. 8. 1 The left clavicle.

the lateral end is flattened and articulates with the acromion of the
scapula. The lateral quarter of the bone shows on its inferior surface
a prominent tubercle known as the conoid tubercle for attachment of
the conoid ligament and lateral to this is the trapezoid ridge, to which
the trapezoid ligament is attached. These two ligaments which
together are known as the coracoclavicular ligament connect the

74

BONES AND JOINTS OF THE UPPER LIMB 75

clavicle with the coracoid process of the scapula. The under surface
of the inner part of the bone shows a deep impression, the rhomboid
fissa which is often visible on radiographs and is the site of attach-
ment of the costoclavicular ligament which unites the clavicle to the
first rib.

THE SCAPULA

The scapula is a large flattened triangular bone lying on the
ptxsterolatcral aspect of the chest and extending from the second to
the seventh ribs. The body possesses a concave anterior surface, the
subscapular fossa, a posterior surface from which the spine of the scapula
projects, a vertebral border medially and an axillary border laterally.
I’he superior border and the vertebral border meet at the superior angle
and tlie vertebral and axillary borders meet at the inferior angle,
riicre is a flattened lateral angle between the axillary and superior
borders which bears the glenoid cavity for articulatioi'* with the head
of the humerus. The part of the scapula bearing the glenoid cavity is
called the head and it is separated by a constriction called the neck
from the rest of the bone. Projecting from the anterior surface of the
head is the coracoid process. The spine of the scapula divides the
posterior surface into ih^esupraspinous and infraspinous fossae. The
lateral end of the spine is expanded and flattened to form the
acromion, with which the clavicle articulates.

THE HUMERUS

The humerus is the longest of the bones in the upper limb; it has
an almost cylindrical shaft with a rounded, medially directed head
and an expanded lower end.

The upper end consists, in addition to the head, of the lesser tuberosity
anteriorly and the greater tuberosity, the most lateral bony point in the
shoulder region. Separating the two tuberosities is the bicipital
groove. Immediately adjoining the margin of the head is the anato-
mical neck but the surgical neck is that part of the shaft which comes
immediately below the head and tuberosities.

The shaft has a roughened elevation, the deltoid tuberosity, in the
middle of its lateral surface into which the deltoid muscle is inserted.
Below this, passing obliquely downwards and forwards is the
spiral groove for the radial nerve.

The lower end of the humerus is expanded transversely and shows
two prominences above the articular portion, the medial and lateral
epicondyles, from which the supracondylar ridges extend proximally.

76

THE APPENDICULAR SKELETON

Supmnor Angim

Superior Angle

Acromion

Process

Coracoid

Process

Glenoid

Cavity

Axillary

Border

Inferior Angie

Fig. 8.3 The left scapula — anterior surface.

BONES AND JOINTS OF THE UPPER LIMB 77

The lateral portion of the articular surface, the capitulum, is rounded
and articulates with the radial head; the medial part, which is
called the trochlea, is deeply grooved and articulates with the ulna.
A deep hollow, the olecranon fossa, is seen immediately above the
trochlea and it accommodates the olecranon when the elbow is
extended. On the anterior surface of the bone opposite the olecranon
fossa is the coronoid fossa which receives the coronoid process when
the elbow is fully flexed.

It will be observed that the medial part of the lower end of the
humerus extends more distally than the lateral so that the axis of
the elbow joint docs not make a right angle with the long axis of the

fossa Epicondyle

1 II

Fig. 8.4 Posterior (I) and anterior (II) surfaces of the
right humerus.

78 THE APPENDICULAR SKELETON

humerus. Thus the forearm and arm are not in the same straight
line when the elbow is extended but make an angle of about 164°
with each other; this is called the carrying angle and it enables objects
carried by hand with the arm outstretched to be more easily swung
clear of the thighs.

THE RADIUS

The radius is the lateral of the two forearm bones and has a
cylindrical head proximal ly and an expanded lower end from which
the styloid process projects distally; this end of the bone is grooved on
its posterior surface where the extensor tendons of the wrist and
fingers pass across it. The neck comes immediately distal to the head

Coronoid

Process

Trochlear

Notch

Radial

Notch

Bicipital

Tuberosity

Styloid
Process of
Radius

Styloid Process
of Ulna

Head of
Ulna

Process

Head of
Radius

Neck of
Radius

1 II

Fig. 8.5 Anterior (I) and posterior (II) .surfaces of the
radius and ulna.

and below this projecting laterally is the radial or bicipital tuberosity
into which is inserted the tendon of the biceps muscle. The shaft

BONES AND JOINTS OF THE UPPER LIMB 79

has a prominent interosseous border from which the interosseous
membrane (see p. 87) stretches across to the ulna.

THE ULNA

The ulna is longer than the radius and lies medial to it. At
its upper end arc two conspicuous processes, the coronoid process and
the olecranon and between these is the deep trochlear notch with which
the trochlea of the humerus articulates. On the lateral side of the
c(3ronoid process is the radial notch for articulation with the head of
the radius at the superior radio-ulnar joint. The lower end is small and
shows the rounded head separated by a shallow groove from the
styloid process which projects distally from the posteromedial aspect
of this part of the ulna. The shaft separates the upper from the lower
end and is united to the radial shaft by the interosseous membrane.

Ulna

Radius

Radius

process
Lunate
TnquetraJ^
Pisiforrri
Hami
Capitate

Styloid process
Scaphoid
Trapezoid
Trapezium

Styloid

process

Pisiform

Triquetral

Hamate

Metacarpals

Phalanges

1 II

Fig. 8.6 Posterior or dorsal (1) and anterior or palmar (II) surfaces of the right
wrist and hand.

THE HAND

The bones of the hand are divided into (i) the carpal or wrist
bones; (2) the metacarpal bones; and (3) the phalanges or bones
of the digits.

80 THE APPENDICULAR SKELEFON

THE CARPAL BONES

The carpus consists of eight bones arranged in two rows, a
proximal and a distal. From the lateral side the proximal row
contains the scaphoid^ the lunate^ the triquetrum and the pisiform.
The distal row in the same order consists of the trapezium, the trape-
zoid, the capitate and the hamate. The pisiform is set somewhal anterior
to the triquetral, the hamate is characterized by a prominent process
directed anteriorly and the capitate is the largest bone in the carpus.
The scaphoid is frequently the site of fracture and its radiographic
demonstration is helped by the movement of ulnar deviation which is
described under movements of the wrist joint.

THE METACARPAL BONES

There are five metacarpal bones, each of which possesses a head
distally, a shaft and, proximally, a base. The first metacarpal
articulates with the thumb and is set on a more anterior plane than
the remaining four.

THE PHALANGES

These short long-bones also have a shaft and two extremities; the
shafts taper distally. There are three phalanges for each finger and
two for the thumb.

JOINTS OF THE UPPER LIMB

THE STERNOCLAVICULAR JOINT

This is a synovial joint between the medial end of the clavicle and
the facet on the lateral aspect of the upper border of the manubrium
of the sternum.

THE ACROMIOCLAVICULAR JOINT

This synovial joint intervenes between the lateral end of the
clavicle and the facet on the medial margin of the acromion of the
scapula. A number of important ligaments strengthen this joint one
of which, the coracoclavicular ligament (p. 74), unites the coracoid
process to the under surface of the lateral part of the clavicle.

THE SHOULDER JOINT

This is a synovial joint of the ball-and-socket type. The hemi-
spherical head of the humerus articulates with the shallow glenoid

RADIOGRAPHIC APPEARANCES OF SHOULDER 8l

cavity of the scapula which is deepened by a fibrocartilaginous ring,
the glenoid labrum, attached round its margin. Hyaline cartilage
covers the articulating surfaces and a capsule, lax to permit a wide
range of movement, encloses the joint. The capsule is strengthened
by ligaments and muscles and some of the tendons of the latter, e.g.
that of supraspinatus, actually blend with it. The synovial mem-
brane lines the capsule and also covers the tendon of the long head
of the biceps muscle (see p. 113) which runs through the joint.

I’he shoulder joint has a wide range of movement : flexion is forward
and medial movement of the arm; extension is backward and lateral
movement of the arm; abduction is raising the arm sideways and, in
combination with scapular movement, raising it above the head and
adduction is movement of the arm towards or across the chest. CVr-
cumduction is a combination in sequence of these movements (as in
skipping) and the remaining movements are external and internal
rotation.

Articular capsule

Long head of
biceps brachii

Greater

tuberosity

Scapula

Humerus -

Glenoid labrum
Articular capsule

Fig. 8.7 Longitudinal .section through the right shoulder joint.

RADIOGRAPHIC APPEARANCES OE THE SHOULDER REGION

The posterior and inferosuperior projections will be described.

The posterior radiograph shows the outer two- thirds of the
clavicle, the scapula and the upper one-third of the humerus, the
acromioclavicular and shoulder joints and the upper ribs and part
of the lung.

The clavicle is seen at the upper part of the radiograph and is

RADIOGRAPHIC APPEARANCES OF SHOULDER

83

84 THE APPENDICULAR SKELETON

separated from the acromion by a gap which represents the acromio-
clavicular joint. The acromion, seen at the lateral end of the spine of
the scapula, intervenes in the radiograph between the humeral head
and the clavicle. The glenoid is shown as an oval shadow and it may
be overlapped to a variable extent by the humeral hq^d. The
coracoid process is seen projecting upwards from the head of the
scapula; it may be superimposed on the glenoid cavity and its
appearance varies considerably according to the position of the
shoulder at the time of the examination. The outlines of the superior,
axillary and vertebral borders of the scapula and its superior and
inferior angles are also shown.

The smooth rounded humeral head projects upwards and medi-
ally and the greater tuberosity is clearly shown on the lateral side
but the lesser tuberosity and the bicipital groove are superimposed
upon the bone and will not be recognized. The deltoid tuberosity
produces a slightly raised and roughened area on the lateral aspect
of the middle of the shaft.

The inferosuperior projection may be taken in various ways; in
cases of injury when abduction may be painful or impossible the
cone of the X-ray tube may be inserted between the elbow and the
flank, the cassette being held on top of the shoulder by the hand of
the uninjured side. The interpretation of this radiograph is facilitated
by first identifying the front; this is done by recognizing the for-
wardly projecting coracoid process. It is then easy to proceed to
the identification of the clavicle, the acromion and the spine of
the scapula. The humeral head and glenoid cavity are seen and the
axillary border of the bone is projected as a shadow running
posteromedially from the glenoid cavity behind I he clavicle willi
which it is sometimes confased.

Ossification of the Shoulder Region

The upper end of the humerus is ossified from three centres, one which
appears during the first year for the head, one for the greater tuberosity
which appears during the third year and one for the lesser tuberosity which
appears during the fifth year. These fuse into one centre during the sixth
year and the single large epiphysis thus formed is separated from the shaft
by the epiphyseal cartilage plate which will be projected as two trans-
radiant lines on the radiograph if the X-ray beam strikes it obliquely.
This appearance is sometimes mistaken for a fracture but careful study
will show that thin white lines of cortical bone form the margins of the
transradiant areas and these would not be seen in fractures. Secondary
ossific centres for the acromion and tip of the coracoid process may be seen
during adolescence.

85

THE ELBOW JOINT

THE ELBOW JOINT

This consists of two joints, the humero-ulnar between the trochlea
of the humerus and the trochlear notch of the ulna, and the humero-
}adial between the capitulum and the radial head. These constitute a
hinge joint and as with all such joints the medial and lateral liga-
ments are strong but the capsule is thin anteriorly and posteriorly.
The synovial membrane is extensive, it lines the capsule and the
coronoid and olecranon fossae and is continuous with the synovial
membrane of the superior radio-ulnar joint.

I’he movements of the joint are flexion, i.e. approximation of the
anterior surfaces of the arm and forearm, and extension, i.e. straight-
ening the elbow.

Fig. 8.10 The left elbow and superior radio-ulnar joints - medial aspect.

THE PROXIMAL RADIO-ULNAR JOINT

This synovial joint of the pivot type is situated between the
circumference of the radial head and a ring made up of the annular
ligament and the radial notch of the ulna. The synovial membrane is
continuous with that of the elbow joint. The movements will be
considered when the inferior radio-ulnar joint is described.

RADIOGRAPHIC APPEARANCES OF THE ELBOW REGION

The posterior and lateral projections will be described. In the
former the elbow is extended and in the latter it is flexed to a right
angle.

86

THE APPENDICULAR SKELETON

I'he posterior projection includes the lower end of the humerus,
the proximal ends of the radius and ulna and the elbow and superior
radio-ulnar joints. On the inner side of the lower end of the humerus
the medial epicondyle is conspicuous and the shadow of the ole-
cranon is superimposed on the trochlea, above which the olecranon
and coronoid fossae produce a triangular transradiancy. The
articular cartilage of the elbow joint produces a parallel translucent
space between the rounded capitulum and the radial head and
between the trochlea and coronoid process. The neck and bicipital

Humerus

Olecrerton and
coronoid fossae
superimposed

Medial

epicondyle

Trochlea

Capitulum

Coronoid
process

Radial head

Radial neck

Bicipital
tuberosity

Ulna
Radius

Humerus Olecranon Trochlea Capitulum Radial

heed

I II

Fig. 8.11 Radiograph of the right elbow joint. Posterior (I) and medial ( 11 ) pro-
jections.

tuberosity of the radius and the superior radio-ulnar joint are
also seen.

The lateral projection of the elbow shows the cpicondyles super-
imposed to a variable extent. The capitulum and trochlea are also
superimposed and present similar curved outlines. The capitulum
can be recognized as it will lie parallel to the articular surface of the
radial head, and it projects for about one-third of its thickness in
front of the anterior surface of the humeral shaft. It will help in
the identification of the capitulum if it is remembered that in the
normal elbow joint prolongation proximally of the long axis of the

THE WRIST JOINT 87

radius will always lead to the capitulum whatever the position of the
elbpw joint.

Ossification of the Elbow Region

Up to the age of about 2 years there are no epiphyseal centres visible in
the elbow region so that a wid(‘ gap appears to separate the humerus
from the forearm bones in the radiograph. 'I’he first centre to appear is
that for the capitulum at 24 years, then at about 5 years the medial
epicondyle and the radial h(‘ad are visible. Next to appear are the centres
for the trochlea and tip of tht' oledanon at 10 yt'ars, followed at 12 years
by the external epicondyle.

THE MIDDLE RADIO-ULNAR JOINT

This consists of the interosseous membrane wliich connects the radius
to the ulna and extends for the greater part of the length of the
shafts of these bones.

THE DISTAL RADIO-ULNAR JOINT

This is a synovial joint between the head of the ulna and the
ulnar notch on the medial side of the lower end of the radius. An
articular disc, the triangular cartilage^ extends from the styloid
process of the ulna to the radius and the two bones arc also united
by the articular capsule.

The movements of the proximal, middle and distal radio-ulnar
joints arc pronation and supination. Pronation is rotation of the radius
round the ulna so that the palm of the hand faces backwards when
the arm is hanging by the side. Supination is rotation of tJie radius
round the ulna so that the palm of the hand faces forwards when the
arm is hanging by the side.

THE WRIST JOINT

The wrist or radiocarpal joint is a synovial joint between the
distal surface of the radius and the triangular cartilage of the distal
radio-ulnar joint above, and the proximal articular surfaces of the
navicular, lunate and triquetral bones below. It will thus be seen
that the lower end of the ulna does not articulate with the carpal
bones and does not form part of the wrist joint.

The movements occurring at this joint are flexion, i.e. forward
movement of the hand; extension, i.e. backward movement of the
hand, abduction and adduction, radial and ulnar deviation respectively,

88

THE APPENDICULAR SKELETON

and circumduction which is a combination in sequence of these move-
ments. Radiographs of the wrist are often taken in ulnar deviation
as the scaphoid is more adequately demonstrated in this position.

The carpal tunnel is a groove on the anterior (palmar) aspect of
the carpal bones bridged over by the transverse carpal ligament. In
the tunnel so formed run the tendons of the flexor muscles and the
median nerve. It is sometimes necessary to demonstrate the bony
part of the tunnel by an axial radiographic projection when search-
ing for a cause of pain in the wrist and hand.

Fig. 8. 1 a Seclion showing wrist, carpal and carponiplacarpal joints.

RADIOGRAPHIC APPEARANCES OF THE WRIST AND HAND

The anterior radiograph of the wrist includes the lower ends of
the radius and ulna, the inferior radio-ulnar joint, the carpal and
the proximal ends of the metacarpal bones. The carpal bones are
seen to be separated by the ‘spaces’ of the intercarpal joints and in
the proximal row of these bones the pisiform is seen to be super-
imposed on the triquetrum. In the distal row of the carpus the
hamate shows an oval white ring caused by its hook. The wrist joint
is seen intervening between the radius and the scaphoid and lunate;
the radial styloid process is observed to extend more distally than
that of the ulna and if the radiograph is not taken in ulnar deviation
the scaphoid will appear foreshortened.

The lateral projection shows clearly the convex surface of the

THE WRIST AND HAND

89

lunate parallel to the articular surface of the radius and its concave
distal surface articulating with the capitate. The pisiform is seen
anteriorly and it is often superimposed on the tuberosity of the
scaphoid.

The anterior projection of the hand shows, in addition to the
carpus, the metacarpal bones and the phalanges. Sesamoid bones
arc usually present in the region of the first metacarpophalangeal
joint.

Hamate

Triquetrum

Pisiform

Ulnar styloid
process

Inferior

radio-ulnar

joint

Superimposed
pisiform and
tuberosity of
scaphoid

Lunate

Fig. 8. 1 3 Radiograph of region of left wrisl. Anterior and lateral projecliofis.

Ossification of the Carpus

A radiograph of the hand and wrist of a newborn child shows wide gaps
between the bone ends. Fhese gaps are occupied by unossified cartilage,
for the carpal bones, the bases of the phalanges and the heads of the
metacarpal bones contain no centres of bone formation at this time.
Centres for the carpal bones appear roughly at yearly intervals from the
appearance of the capitate in the ist year to the 8th when the trapezoid
begins to ossify; there is then an interval until the 12 th year when the
ossific centre fbr the pisiform appears. The ossific centres at the lower
ends of the radius and ulna are usually seen at 2 and 8 years respectively.

For the estimation of what is called the skeletal age the whole hand in-
cluding the terminal phalanges should be included in the radiograph in
infants but for children up to about 8 years the carpus is likely to suffice;
above this age the elbow will probably also be required.

G

90

THE APPENDICULAR SKELETON

BONES AND JOINTS OF THE LOWER LIMB

THE HIP BONE AND PELVIS

Each hip or innominate bone is composed of three bones, the ilium,
the pubis and the ischium. The two hip bones together with the
sacrum and coccyx make up the pelvic girdle which connects the lower
extremities with the trunk.

The ilium is a broad somewhat fan-shaped sheet of bone, its upper
border, known as the iliac crest, extends from the anteiior superior
iliac spine to the posterior superior iliac spine. Below the anterior superior
spine is the anterior inferior iliac spine and on the medial surface of the
posterior part of the bone is a large roughened area where the ilium
articulates with the sacrum at the sacro-iliac joint. Below this the
lower border of the bone is deeply indented and forms the greater
sciatic notch. The body of the ilium constitutes the upper part of the
acetabulum or socket for the hip joint.

illse crett

Iliac tubarch

Postarior
suparlor spina

Posterior
inferior spina

Great sciatic notch

Body of Ischium

Ischial spine

Small sciatic notch

Ischial tuberosity

Iliac crest
.Ala of Ilium

Anterior
superior spine

Body of ilium

Anterior
inferior spine

Acetabulum
llio~pectineal
eminence

<Z^Body of pubis
Pubic tubercle

Superior ramus
of pubis

Inferior ramus
of pubis

\ Inferior ramus of Ischium
Superior ramus of Ischium

Fig. 8.14 The right hip bone — lateral aspect.

Obturator forafnen

The pubis has a body and two rami. The body lies anteriorly and
articulates with that of the opposite side at the pubic symphysis

BONES AND JOINTS OF THE LOWER LIMB Ql

which therefore lies on its medial side. The superior ramus runs
laterally from the body to take part in the formation of the accta-
bufum and the inferior ramus runs downwards to meet the inferior
ramus of the ischium.

The ischium is the lowest portion of the pelvis; it possesses a body
which forms the lower part of the acetabulum and from it the ischial
spine projects medially. The superior ramus projects downwards from
the body and bears the broad ischial tuberosity on which the weight
of the body is borne when sitting. The inferior ramus of the ischium
arises from the superior ramus and extends forwards to meet the
inferior pubic ramus; it is separated from this by a cartilaginous
plate until about 8 years of age.

The ischium and pubis together enclose a large opening called the
obturator foramen which is occupied during life by a membrane.

The acetabulum is the deep cup-shaped socket with which the head
of the femur articulates and it is composed of parts of each of the
three bones which constitute the hip bone. During childhood
the bones are separated from each other in the acetabulum by the
triradiaie cartilage^ which ossifies soon after puberty.

Promontory 1 1
of Sacrum -/ U ,,

5acfO-/7iac-. V i\kVi

llio-pectineal
Line

Symphysis Pubis Pubic Arch

Fig. 8.15 The pelvis — anterior aspect,

Ischial
Spine

Acetabulum
Obturator
Foramen
Ischial Tuberosity

Anterior
Superior
y Spine

Anterior
Sacral
Foramen

THE PELVIS

The pelvis is divided into the false pelvis and the true pelvis. The
false pelvis is fbrnied by the iliac bones laterally and the sacrum
posteriorly. The true pelvis is a bony ring formed by the sacrum and
coccyx behind and the ischium and pubis on each side. It has an

THE APPENDICULAR SKELETON

92

inlet, a cavity and an outlet. The anteroposterior measurement of
the pelvic inlet is called the true conjugate and the transverse diameter
cf the inlet is called the transverse conjugate. Both these measurements
can be obtained radiographically and arc of importance in ob-
stetrics. *

There are certain sexual differences in the pelvis. The female pelvis
is wider and less deep than the male, the inlet is more circular and
the subpubic arch is wider. The ischial tuberosities are further apart
and the sciatic notches are wider and shallower. The female pelvis
is adapted in this way for the passage of the foetal head during
childbirth. In the male the bones are usually bigger and heavier but
the pelvic cavity is relatively smaller.

JOINTS OF THE PELVIS

THE SACRO-ILIAC JOINT

This is a synovial joint between the articular surface of the ilium
and the upper part of the lateral surface of the sacrum. The capsule
is re-inforced by strong ligaments.

THE SYMPHYSIS PUBIS

The two pubic bones articulate with each other at the symphysis
pubis. This joint consists of a fibrocartilaginous pad between the
bones, and ligaments which unite them above and below.

BONES OF THE LOWER LIMB

THE FEMUR

The femur is the longest bone in the skeleton; it has an upper and
a lower end and a roughly cylindrical shaft.

The upper end bears the hemispherical head in which is a roughened
depression, the fovea; a ligament is attached here which binds the
head of the femur to the pelvis. The head surmounts the neck which
makes an angle of about 125° with the shaft. At the junction of the
neck with the shaft the two trochanters are found, the greater on the
outer aspect and the lesser at a lower level on the postero-medial
aspect of the bone. Posteriorly between the trochanters is a promi-
nent ridge known as the intertrochanteric crest.

The lower end of the bone is wide and bears two eminences known

BONES OF THE LOWER LIMB

93

as the condyles which are separated posteriorly by the intercondylar
notch. At the highest part of the medial condyle the adductor tubercle
projects and anteriorly the condyles blend with each other forming
the patellar surface (for articulation with the patella or knee cap).
There is a flattened area on the posterior surface of the bone above
the condyles known as the popliteal surface] this forms the floor of the
popliteal space through which the popliteal nerves and vessels run.

Trochanteric
Fosta

Head

Neck

Intertrochanteric
Line

Shafts

Lateral

Condyle

Gluteal

Ridge

Great

Trochanter

Intertrochanteric

Crest

Popliteal

Surface

Articular Surface
for Patella

Medial

Condyle Intercondylold
Notch

I II

Fig. 8.16 Anterior (I) and posterior (IT) surfaces of the right femur.

THE PATELLA

The patella or knee cap is a sesamoid bone in the tendon of the

THE APPENDICULAR SKELETON

94

quadriceps femoris muscle. It is triangular in shape and articulates
posteriorly with the patellar surface of the femur when the knee is
extended ; when the joint is flexed it articulates with the anterior
surfaces of the femoral condyles. Its anterior surface is subcutaneous
but is separated from the skin by the prepatellar bursa.* Xhe quad-
riceps tendon blends with the bone, and the continuation of the
tendon which is inserted into the tibial tuberosity is known as the
patellar ligament.

THE TIBIA

The tibia is the inner of the two bones of the leg and consists of an
upper and a lower end and a shaft.

Medial

Condyle

PopHteel

Surfece

Spine Leteral Condyle

Head of
Fibula

Medial

Malleolus

FIBULA

l B Anterior
Border

Medial

Condyle

Tubercle

Subcutaneous
Ml Surface

Medial

Malleolus

I Lateral Malleolus U

fig. 8.17 Posterior (I) and anterior (II) surfaces of the
right tibia and fibula.

The Upper end is expanded to form the tibial condyles each of which
has a slightly concave upper surface and takes part in the formation

BONES OF THE FOOT

95

of the knee joint. Between the two condyles the tibial spine projects
upwards and ends in two pointed tubercles. Projecting anteriorly
from the bone below the two condyles is the tibial tuberosity to which
the patellar ligament is attached.

The lower end takes part in the formation of the ankle joint and
has a downward prolongation from the medial surface known as the
medial malleolus. On the lateral aspect of the lower end is a facet for
articulation with the lower end of the fibula.

The shaft has a subcutaneous surface directed anteromedially and
a prominent anterior border.

THE FIBULA

The fibula is the outer of the two leg bones and has an upper and
a lower end and a shaft.

The upper end is known as the head and articulates with the upper
end of the tibia but it does not take part in the knee joints. Certain
ligaments and muscles are attached to it.

I’hc lower end, known as the lateral malleolus, projects down beyond

the medial malleolus and articulates both with the lateral surface
of the lower end of the tibia and with the lateral aspect of the talus.

Between the two ends is the long slender shaft to which are
attached several muscles and the interosseous membrane which
binds the tibia and fibula together.

BONES OF THE FOOT

THE TARSAL BONES

The calcaneum is the largest of the tarsal bones; it forms the heel

THE APPENDICULAR SKELETON

96

and articulates with the talus above and the cuboid in front. A
process known as the sustentaculum tali projects medially and gives
attachment to the powerful spring ligament which assists in the
formation of the longitudinal arch of the foot. The posterior part of the
bone is known as the tuberosity and the Achilles tendon (p. 118) is
inserted into it. The upper surface has anterior, middle and posterior
facets for articulation with the under surface of the talus. A deep
groove, the sulcus calcanei^ crosses the bone in front of the posterior
articular facet.

The talus intervenes between the lower ends of the tibia and
fibula above and the calcaneum and navicular below. It has a head,
a neck and a body. The head projects anteriorly and articulates with
the navicular and is separated from the body by the neck. The
body constitutes the greater part of the bone; its upper surface takes
part in the formation of the ankle joint, and below it articulates with
the sustentaculum tali and posterior articular facet of the calcaneum.
Projecting posteriorly from the body is the posterior process and somc-

Fig. H. 19 The bones of the right foot niecliaJ aspect showing longi
ludinal aich.

times part of this may remain as a separate bone, when it is known
as the os trigonum.

The navicular lies on the inner side of the tarsus and intervenes
between the talus behind and the three cuneiform bones in front.

The cuneiform bones are three in number and articulate posteriorly
with the navicular and anteriorly with the medial three metatarsal
bones.

The cuboid lies on the outer side of the tarsus and intervenes
between the calcaneum behind and the two lateral metatarsals in
front.

JOINTS OF THE LOWER LIMB

97

THE METATARSAL BONES

There are five metatarsal bones. The first is the tliickest and the
second is usually the longest. The fifth has a prominent tuberosity
on the lateral side of its base.

THE PHALANGES

There are two phalanges in the great toe and three in each of the
other four toes.

JOINTS OF THE l.OWER LIMB

THE HIP JOINT

The hip joint is a synovial joint of the ball-and-socket variety. The
loundcd femoral head articulates with the deep cup-shaped aceta-
bulum of the innominate bone, 'fhe acetabulum is deepened in the
same w'ay as the glenoid of the scapula by a ring of fibrocartilage
around its circumference known as the acetabular labrurn. Articular
cartilage covers the head of the femur, except for the fovea where the
Hgamentum teres is attached. The acetabulum has a horsc-shoe-shaped
articular surface covered by cartilage, and a non-articular portion
bridged by the transverse ligament of the hip to which the liga-
mentuin teres is attached. I'he capsule of the joint is strong and is
reinforced by several important ligaments which connect the femur
to the ilium, the ischium and the pubis.

The movements of the hip joint are flexion, i.e. approximation of
the thigh towards tlie abdomen; extension^ i.e. backward movement
of the thigh; abduction, i.e. the movement which separates the legs,
and adduction, i.e. the movement of the thigh towards the midline;
circumduction is a combination of all these movements. External and
internal rotation need no special description.

RADIOGRAPHIC APPEARANCES OE THE HIP REGION

The radiograph may be a posterior view centred over one hip or
it may be a projection of the entire pelvis so that the two hips may
be compared. The subject is placed with the thigh slightly internally
rotated by approximating the toes, since in this position, the neck
of the femur is shown in its entirety whereas in external rotation,
when the foot is directed outwards, the neck is greatly foreshortened.

The outline of the bony parts is shown and as in all .synovial

gS THK APPENDICULAR SKELETON

joints the articulating surfaces arc seen to he parallel and separated
by a narrow space occupied by the articular cartilage which casts
no shadow. It is customary to study ^ShentorCs line' when scrutinizing
radiographs; this is the smooth curve which may be traced in the
normal hip along the inferior surface of the femoral neck and
upper border of the obturator foramen.

Sacro-iliae

joint

Sacrum

Acetabulum

Fovea

capitis

Greater

trochanter

Obturator

foramen

Lesser

trochanter

Symphysis

pubis

Shenton's

line

Fig. 8.30 Radiograph of the pelvis. Posterior projection.

Ossification of the Hip Region

The ossific centre for the femoral head appears during the first year and
those for the greater and lesser trochanters about the fourth and ninth
years respectively. During childhood the ilium, ischium and pubis are
separate bones because the triradiate cartilage separates them at the
acetabulum and the inferior rami of the pubis and ischium arc similarly
separated. In adolescence centres arc also seen for the iliac crests and
ischial tuberosities.

THE KNEE JOINT

The knee joint is a synovial joint of the hinge variety and three
bones, the femur, the tibia and the patella enter into its formation.
The condyles of the femur and the upper surface of the tibial

lOO

THE APPENDICULAR SKELETON

condyles articulate with each other and the patella articulates with
the anterior aspect of the lower end of the femur, the joint surfaces
being covered by articular cartilage. The capsule of the joint is
strengthened by several important ligaments, among them the
patellar ligament and the medial and lateral ligaments, "^here are
certain intra-articular structures the most important of which are
the anterior and posterior cruciate ligaments and the medial and lateral
menisci for semilunar cartilages). The cruciate' ligaments run obliquely
from the inter-condyloid notch of the femur to the upper surface of
the tibia and their function is to limit the extremes of extensions and
flexion respectively. 'Fhc menisci are half-moon-shaped structures
attached to the upper surface of the tibial condyles. The synovial
membrane is extensive and extends upwards behind the patella and
lower part of the quadriceps tendon.

The movements of the knee atc flexion, i.e. the approximation of
the calf to the back of the thigh, and extension, i.e. straightening the
limb.

RADIOGRAPHIC APPEARANCES OF THE KNEE REGION

A posterior and a lateral radiograph are usually taken. In the
extended position the lower pole of the patella usually lies about
\ inch (i centimetre) above the joint line and it is in this position that
the first radiograph will be taken. The student will appreciate that
although the fibula and the superior tibiofibular joint are shown
they take no part in the formation of the knee joint.

The posterior view shows the parallel joint surfaces, the deep inter-
condylar notch of tlie femur and the tibial spine. The head of the
fibula partly overlaps the lateral tibial condyle and the patella is
superimposed on the lower end of the femur. Superimposed on the
lateral femoral condyle of the femur a circular shadow about 5 mm.
in diameter is sometimes seen; this is the fahella, a sesamoid bone in
the lateral head of the gastrocnemius muscle.

The lateral projection shows the femoral condyles partly super-
imposed on each other and the fibula overlapping the tibia to a
variable extent. The patella lies above the anterior surface of the
femoral condyles in extension, but in flexion it is seen to articulate
with the distal surface of the lower end of the femur. The tibial
tuberosity is seen on the anterior aspect of the bone; it is most
conspicuous in adolescence when it is a separate ossific centre.

THE KNEE

101

I II

Fig. 8.23 Radiograph of left knee region. (I) Posterior and (II) lateral
projections.

Ossification of the Knee Region

Ossific centres for the lower femoral and upper tibial epiphyses are
present at birth. Centres for the patella and head of the fibula appear at
about 5 years. A separate centre for the tibial tuberosity appears at about
10 years and fuses with the upper epiphysis to form the head of the bone
from which it projects as a tongue like process.

THE TIBIOFIBULAR JOINTS

The tibia and fibula articulate at their upper ends by a synovial
joint, the superior tibiofibular joint and, at their lower ends, by a
fibrous joint, the inferior tibiofibular joint \ between their shafts
stretches the interosseous membrane,

THE ANKLE JOINT

The ankle joint is a synovial joint of the hinge variety between

102

THE APPENDICULAR SKELETON

the medial malleolus, the distal end of the tibia and the lateral
malleolus of the fibula above and the upper surface of the body of
the talus below. The articular surfaces are covered with cartilage
and the capsule is strengthened by a number of ligaments, the most
important of which are those on the medial and lateral ^pects.

The movements of the ankle joint are dorsijlexion and plantar-
flexion. In the former the foot is drawn up towards the anterior
aspect of the tibia and in the latter it is moved in the opposite
direction.

Interosseous

Membrane

Fibula

Interosseous

Ligament

Ankle Joint

Talus

Lateral

Ligament

Calcaneus

Deltoid

Ligament

Fig. 8.24 Coronal section through the ankle joint.

JOINTS OF THE FOOT

The joint between the talus and the calcaneum is called the
subtaloid joint and those between the talus and navicular and the
calcaneum and cuboid are known collectively as the midtarsal joint.
The movements of these joints are inversion in which the sole of the
foot is directed inwards and the inner border of the foot is raised
and eversion in which the outer border is raised and the sole is turned
outwards.

104 THE APPENDICULAR SKELETON

- Other joints in the foot are the intertarsal, the tarsometatarsal, the
metatarsophalangeal and the interphalangeal and they do not
require separate description.

THE ARCHES OF THE FOOT

There are two arches of the foot, the longitudinal and the trans-
verse. The longitudinal arch (see Fig. 8.ig) has a medial and a lateral
side, the former is the higher and is composed of the calcaneum, the
talus, the navicular, the cuneiforms and the inner three metatarsals.
The lateral side of the arch is composed of the calcaneum, the cuboid
and the fourth and lifth metatarsal bones. 'Fhe transverse arch (see
Fig. 8.26) is situated in the region of the tarsometatarsal joint. 'Fhe
arches are maintained by the shape of the bones, certain ligaments,
the tendons of certain muscles of the leg and some of the intrinsic
muscles of the foot.

Fig. 8.2(3 Section tliroiigh the foot to show the transverse arch.

RADIOGRAPHIC APPEARANCES OF THE ANKLE AND FOOT

The posterior view shows the lower ends of the tibia and fibula
with the inferior tibiofibular joint and below these the talus grasped
in the socket formed by the malleoli and the distal surface of the

THE FOOT

105

Setsmold

bone

lit metatariMl

5th metatarsal

Medial

cuneiform

Navicular

Cuboid

Midtarsal

loint

Talus

Calcaneum
Ankle joint

Tibia

Fibula

Fig. 8.27 Radiograph of llie* right foot. Plantar projection. ’

ti])ia. The joint ‘space’ is seen separating the tibia and talus but the
lateral malleolus usually overlaps the talus laterally.

The lateral projection of the ankle shows most of the tarsal bones
although the cuneiforms and anterior part of the cuboid will be
superimposed. The subtaloid and midtarsal joints are seen and the
talus and calcaneum are viewed in profile.

In projections of the foot the tarsal bones, the metatarsals and the
phalanges are seen. Sesamoid bones are present in the neighbour-
hood of the head of the first metatarsal bone.

Ossification of the Ankle Region

Centres are usually present in the talus, calcaneum and cuboid at birth.
H

I06 THE APPENDICULAR SKELETON

The navicular is the last tarsal bone to ossify and a centre usually appears
by 4 years, by this time the lower end of the tibia and fibula have also
appeared and at about lo years of age a secondary centre appears for the
tuberosity of the calcaneum.

9

The Muscular System

The division of muscles into voluntary (striped) and involuntary
(unstriped) varieties has already been described (Chapter 3).

A voluntary muscle has a belly consisting of bundles of muscle-
fibres and it is attached by its origin and insertion to bone, cartilage,
ligaments or skin. When a muscle contracts the fibres increase in
girth and shorten thus approximating the origin, i.e. the fixed point
from which it acts, to the insertion. The insertions of some muscles,
for instance the flexors and extensors of the fingers, are at some
distance from their bellies and in such cases fibrous tendons connect
the muscles to their insertions. Some muscles end in sheets of
fibrous tissue called aponeuroses (sing, aponeurosis), and part of the
abdominal wall, for example, w* formed by the aponeurosis of the
external oblique muscle.

For movements to occur in a co-ordinated fashion contraction of
the prime mover (as the principal muscle concerned is called) must be
accrjmpanied by relaxation of its antagonist (the muscle or group of
muscles which have the opposite action). In some cases the full
effect of the contraction of the prime mover will only be produced if
fixation muscles steady the bone from which it arises. Thus when the
shoulder is abducted the scapula must be fixed or the weight of the
limb will cause it to rotate; similarly in walking the pelvis must be
braced.

Muscles are covered and often ensheathed by fibrous tissue known
as the deep fascia. The superficial fascia is the layer of fatty areolar
tissue which intervenes between the skin and the deep fascia.

It is beyond the scope of this book to list or describe more than a
few voluntary muscles.

MUSCLES OF THE HEAD AND NECK

The cranium is covered by a musculo-aponeurotic sheet and the
face is composed of the muscles of facial expression and the muscles

107

io8

TllK MUSCULAR SYSIKM

of mastication. I’he superficial muscles of the neck consist of the
platysma, the trapezius and the sternomastoid. On a deeper plane are
the muscles attached to the hyoid bone, some of which pass upwards
to form the floor of the mouth and others pass downwards to be
inserted into the manubrium of the sternum. The deepest muscles
run up the anterior aspect of the vertebral bodies and are known as
the prcvcrtebral muscles.

TRAPEZIUS

I’his muscle has an extensive origin which stretches from the
occiput to the spinous process of the twelfth thoracic vertebra; it is

Temporal Muscle Frontalis

inserted into the spine of the scapula and the clavicle. The trapezius
is an elevator of the shoulder and a rotator of the scapula.

STERNOMASTOID

This muscle runs obliquely up the neck and arises from the

MUSCLES OF THE TRUNK

109

manubrium of the sternum and the medial third of tlic upper
surface of the clavicle. It is inserted into the base of the mastoid
prodess and in its course it produces a visible prominence on each
side of the neck, dividing it into the anterior and posterior triangles.
Its anterior margin follows approximately the course of the common
carotid artery and the internal and external carotid arteries into
which this vessel divides. The action of the sternomastoid when
working singly, is to tilt the head towards the shoulder and rotate
it to the opposite side; when acting together the muscles flex the
head on the vertebral column and in forced inspiration they help to
elevate the thorax.

MUSCLES OF THE TRUNK

The superficial muscles of the back arc the trapezius and tlie latis-
slmus dorsi. Beneath these is the sacrospinalis which forms a continuous
band from the occiput to the sacrum, lying in the angle between the

Trapeiius

Acromion

Process

Deltoid

Pectoralis

Major

Biceps

Serratus

Anterior

External

(i) Muscle

Oblique

(2) Aponeurosis

Rectus Sheath

Inguinal

Ligament

Superficial
Inguinal Ring

Spermatic Cord

Sternomastoid

Coracoid

Process

Pectoralis

Minor

Serratus

Anterior

Latisslmus

Dorsi

Linea Alba

Rectus

Abdominis

Internal

Oblique

Deep

Inguinal Ring

Inguinal Canal

Conjoined

Tendon

Fig. 9.2 The muscles of the front of the thorax and
(I) Superficial. (II) Deep.

anterior abdominal wall.

no

THE MUSCULAR SYSTEM

spinous processes and the transverse processes of the vertebrae, this
muscle is an extensor of the spine and plays an important part in the
maintenance of posture.

The anterior abdominal wall and the flanks consist of paired flat
muscles, their sheaths and the aponeuroses (tendinous sheets) that
arise from them. The reclus abdominis is one of these and each runs
between the lower costal cartilages and the pubic bones. Each is
enclosed in a strong sheath and the two muscles are connected in the
mid line by the linea alba, a fibrous band extending from the xiphoid
process to the symphysis pubis.

Another muscle of the anterior abdominal wall is the external
oblique which is more laterally situated than the rectus muscle. Its
fibres run from the lower ribs to the iliac crest, to the pubis and to
the aponeuroses which blend with the anterior layer of the rectus
sheath.

The inguinal ligament. The lower margin of the aponeurosis of the
external oblique stretches as a fibrous band between the anterior
superior iliac spine and the tubercle on the anterior aspect of the
body of the pubis. It corresponds in position to the overlying fold of
the groin.

The inguinal canal. The lower part of the abdominal wall is per-
forated, in the male, by the inguinal canal which lies above the
inner half of the inguinal ligament. This canal transmits several
structures which pass between the scrotal* contents and the pelvis
and it is one of the sites at which a ‘rupture’ or hernia commonly
occurs. (A rupture, in this connection, is the passage of an abdominal
organ or part of an organ through a weak place in the abdominal
wall.)

THE DIAPHRAGM

This is a dome-shaped musculotendinous sheet which separates
the abdominal and thoracic contents. It arises from the xy phi-
sternum, the lower six pairs of ribs and costal cartilages, the fascia
covering the muscles of the posterior abdominal wall and the two
crura (sing, crus), which are tendinous origins from the bodies of the
lumbar vertebrae. The muscle fibres converge to be inserted into the
central tendon which they surround. The diaphragm is pierced by
the inferior vena cava at the level of the eighth thoracic vertebra, by
the oesophagus at the tenth and by the aorta, thoracic duct and

• The scrotum is a musculocutaneous bag in which are the testes, the male sex
glands (see page 219).

MUSCLES OF THE TRUNK

azygos vein, all of which passPthrough the same orifice, at the level of
the twelfth thoracic vertebra.

The diaphragm is related above, on each side, to the pleura
(p. 152) and in the middle to the pericardium (p. 123). These
separate it from the bases of the lungs and heart respectively. The
inferior surface of the diaphragm is covered by peritoneum (p. 184)
and is closely applied to the upper surface of the liver, kidneys,
suprarenal glands, the fundus of the stomach and the spleen.

The functions of the diaphragm are concerned with breathing and
intra-abdominal pressure. During inspiration the diaphragm con-
tracts and thus descends and draws air into the chest; in expiration
it relaxes and the intra-abdominal pressure elevates it. Contraction
of the diaphragm raises intra-abdominal pressure and it therefore
assists in defaecation, micturition and parturition.

The diaphragm is supplied by the phrenic nerves, which arise
from the cervical part of the spinal cord and by the lower intercostal
nerves. Paralysis of one side of the diaphragm may be caused by a
lesion in the neck or chest on that side involving the phrenic nerve
and results in elevation and failure to descend (i.e. contract) on
inspiration. Fluoroscopy is often used for studying diaphragmatic
movement.

I 12

THE MUSCULAR SYSTEM

USCLES OF THE SHOULDER GIRDLE

These muscles are concerned with the movements of the scapula
and shoulder. They form the anterior and posterior boundaries of
the axilla as the angle between the arm and the side of the chest is
called. The axilla contains lymph nodes and the blood ^fessels and
nerves of the upper limb; it is bounded by the anterior axillary
fold, made up largely of the pectoralis major, and the posterior
axillary fold, largely composed of the latissimus dorsi.

PECTORALIS MAJOR AND MINOR

The pectoralis major covers nearly half of the front of the chest
and as it passes laterally to its insertion it forms the anterior axillary
fold. It arises from the medial half of the clavicle, from the sternum
and upper seven costal cartilages and from the aponeurosis of the
external oblique muscle (of the abdomen), and it is inserted into the
lateral lip of the bicipital groove of the humenfs. Its actions are to
adduct and internally rotate the arm. Deep to the pectoralis major
is the pectoralis minor which runs from the ribs to the coracoid
process.

DELTOID

The deltoid covers the shoulder joint and arises from the outer
one-third of the clavicle, the acromion and the spine of the scapula.
Its fibres converge below to their insertion on the lateral aspect of
the humerus at the deltoid tuberosity. The action of the muscle is to
abduct the arm but this movement has to be initiated by the
siipraspinatus. Fifrthermore, the deltoid can only abduct to a right
angle and to raise the arm higher than this rotation of the scapula is
necessary.

SUPRASPINATUS

This muscle arises from the supraspinous fossa of the scapula; it
runs laterally across the shoulder, where its tendon blends with the
capsule of the joint, to be inserted into the highest impression on the
greater tuberosity of the humerus. It acts with the deltoid as an
abductor of the shoulder.

SUBSCAPULARIS

The subscapularis arises from the subscapular fossa on the anterior

MUSCLES OF THE UPPER ARM II3

aspect of the scapula and its fibres pass laterally to their insertion into
the lesser tuberosity of the humerus.

^^USCLES OF THE UP£^R ARM

The muscles of the arm are divided into those of the anterior or
flexor compartment and those of the posterior or extensor compart-
ment. These groups are separated by intermuscular septa which
extend from the deep fascia to the bone. The anterior compartment
consists of the biceps brachii and the brachialis and the posterior
compartment contains only the triceps brachii.

BICEPS BRACHII

This muscle arises by two heads of origin and derives its name
from this fact. It forms the muscle belly on the front of the arm; its
long head arises from the supraglcnoid tuberosity of the scapula as a
tendon which passes laterally through the shoulder joint and the
short head arises, as a tendon also, from the coracoid process. The
long head occupies the bicipital groove after leaving the shoulder
joint, and in the upper one-third of the arm both heads of origin give
place to the muscle bellies which end in a tendinous insertion into
the bicipital tuberosity of the radius. The biceps is a powerful
flexor of the elbow and supinator of the forearm.

BRACHIALIS

This muscle lies in front of the elbow joint. It arises from the front
of the lower half of the humerus and is inserted into the coronoid
process of the ulna. The brachialis is a flexor of the elbow.

TRICEPS BRACHII

This muscle is an antagonist of the biceps brachii and covers the
back of the arm. As its name suggests it arises by three heads; one is
tendinous and springs from the infraglenoid tuberosity of the
scapula and the other two, the medial and lateral heads, arise from
the posterior aspect of the humerus. The muscle ends in a tendon
which is inserted into the olecranon process of the ulna. Triceps
brachii is the powerful extensor of the elbow.

The forearm is also divided into flexor and extensor compart-
ments. The muscles in these compartments are separated into
superficial and deep groups. The superficial group of flexors arises
from the medial epicondyle of the humerus and the d^ep group
arises from the interosseous membrane and the forearm bones.
Many of these muscles are inserted into bones of the carpus or hand
and their muscle bellies give way to tendons just above the wrist.

The superficial group of the extensor compartment arises from
the lateral epicondyle and the muscles are inserted for the most part
into the metacarpal bones and phalanges. The deep muscles arise
from the interosseous membrane and the forearm bones and are
principally inserted into the thumb.

^ MUSCLES OF THE HAND

There are certain muscles confined to the hand which arc
responsible for intricate movements of the thumb and fingers. Some
of these produce a visible prominence on the radial side of the palm

MUSCLES OF THE THIGH II5

known as the thenar eminence and some produce an elevation on
the ulnar side known as the hypothenar eminence.

MUSCLES OF THE THIGH

These may be grouped as those of the front, back and medial sides
of the thigh and those of the gluteal region.

FRONT OF THE THIGH

SARTORIUS

This muscle is also known as the tailor’s muscle and it stretches
from the anterior superior iliac spine to the medial side of the upper
tibia. It forms the roof of a groove between the vastus medialis and
the adductors known as the adductor canal, in which the femoral
vessels run. 'J’liis muscle is a Ilexor of the hip and knee.

PSOAS

This muscle arises from the transverse processes and bodies of the
lumbar vertebrae and intervertebral discs and it runs downwaids
and laterally, passing behind' the inguinal ligament and entering the
thigh as a strong ligament which is inserted into the lesser trochanter
of the femur.

ii6

ILIACUS

THE MUSCULAR SYSTEM

The iliacus arises from the iliac fossa and its fibres pass down along
the lateral side of the psoas tendon into which part of it is inserted ;
the rest is inserted into the femur immediately below the lesse4
trochanter. '

Both the psoas and iliacus are flexors of the hip.

QUADRICEPS FEMORIS

This muscle consists as its name suggests of four parts known as the
rectus femoris, the vastus rnedialis, the vastus intermedius and the vastus
lateralis. These all have a common tendon of insertion into the
upper, medial and lateral borders of the patella from which they
are connected to the tibial tuberosity by the patellar ligament.

Anterior

Superior

Spine

Inguinal

Ligament

Iliacus and
Psoas

Sartor ius

Rectus

Femoris

Vastus

Lateralis

Patella

Ligamentum

Patellae

Pectineus
Pubic Spine

Adductor

Longus

Adductor

Magnus

Gracilhs

Adductor

Magnus

Cracillis

Vastus

Medius

Semi-

membranosus

Gastrocnemius
(Medial Head)

Gluteus

Medius

Gluteus

Maximus

Vastus

Lateralis

Biceps

Semi-

tendmosus

Popliteal

Artery

Gastroc-

nemius

(Lateral

Head)

Fig. 9.7 The muscles of the right
thigh. Anterior aspect.

Fig. 9.8 The muscles of the right
thigh. Posterior aspect.

The rectus femoris arises from the anterior inferior iliac spine and
the bone immediately above the acetabulum. The vasti arise from
the femoral shaft and these muscles are powerful extensors of the
knee. In addition the rectus femoris is a flexor of the hip. ^

MUSCLES OF THE THIGH

BACK OF THE THIGH

117

THese muscles consist principally of those arising from the ischial
■tuberosity which are inserted into the upper end of the tibia and
fibula. They are called the hamstrings and they merge into tendons
which pass behind the knee lying on either side of the upper part of
the popliteal space. The popliteal artery, vein and nerves pass through
this space, the lower part of which is bounded by the two heads of
the gastrocnemius muscle. The hamstrings flex the knee and extend
the hip.

Vastus
Median s

Tendon of
Biceps

Patella

Peroneus

Longus

Extensor

Digitorum

Longus

Tibialis

Anterior

Extensor

Hallucis

Longus

Lateral

Malleolus

Semi-

tendinosus

Ligamentum

Patellae

Semi-

membranosus

Gracilis

Subcutaneous
Surfd^e of Tibia

. Gastrocnemius
(Medial Head)

- Soleus

Flexor

Digitorum

Longus

Medial

Malleolus

Biceps

Popliteal

Artery

Gastrocnemius
(Lateral Head)

Soleus

Peroneus

Longus

Tendon of
Achilles

Lateral

Malleolus

Fig. 9.9 The muscles of the right leg. Fig. 9.10 The muscles of the right
Anterior aspect. leg. Posterior aspect.

MEDIAL SIDE OF THE THIGH

The adductors of the hip constitute the muscles of the medial side
of the thigh and they run from the ischium and pubis to the femur,

THE MUSCULAR SYSTEM

ii8

where they are inserted into a narrow area which stretches from the
lesser trochanter above to the adductor tubercle below.

GLUTEAL REGION

The gluteal region or buttock is composed of several powerful
muscles which stretch from the back of the sacrum and ilium to the
upper part of the femur; their functions are to extend and abduct
the thigh and they play an important part in the maintenance of
posture and in walking. Under cover of these muscles are the short
rotators of the hip which arise within the pelvis and are inserted
into or near the greater trochanter.

MUSCLES OF THE LOWER LEG

These are divided by the bones and interosseous membrane into
an anterior and a posterior compartment. Tlie anterior muscles
dorsiflex the ankle and extend the toes. The posterior group consists
of a superficial layer comprising the gastrocnemius^ whose two
heads form the boundaries of the lower part of the popliteal fossa,
and the soleus. The two muscles end in a common tendon, the
Achilles tendon^ which is inserted into the tuberosity of the calcancum.

The deep layer of the posterior group consists of the long flexors
of the toes and the tibialis posterior, the latter is a powerful invertor of
the foot and plantar-flexor of the ankle.

10

The Circulatory System

The circulatory system is made up of the heart, a powerful
muscular organ which pumps blood round the body, the arteries and
their small branches, the arterioles, which carry blood away from the
heart, the vems and the venules which return blood to the heart and
the capillaries which intervene between the arterioles and the venules.
The circulation consists principally of two parts, the greater or
systemic circulation and the pulmonary or lesser circulation. Mention will
be made later of the portal circulation which is part of the systemic.

I . The Arteries. These consist of three coats, an outer of fibrous
tissuq. a middle of unstriped muscle, and elastic tissue and an inner
of flattened endothelial cells. The calibre of the smaller arteries is
under the control of the nervous system. Thus the amount of blood
reaching an organ can be increased by dilating the arteries and the
reverse effect is produced by constricting them; these processes are
called vasodilatation and vasoconstriction respectively. The arterial
blood pressure is determined by various factors such as the elasticity of

119

120

THE CIRCULATORY SYSTEM

the arteries, the state of vasoconstriction and vasodilatation ol the
smaller vessels and the force of the cardiac pulsation.

2. The Veins. These similarly consist of three coats but they have
much less muscular and elastic tissue in their walls than arteries and
at intervals crescentic valves are found within them. Tljese^yarlves
prevent the flow of blood in the reverse direction and thus they
assist the return of blood to the heart. Blood is propelled along the
veins partly by suction caused by inspiratory movements of the
thorax, and partly by the massaging action resulting from the con-
tractions of the voluntary muscles of the body during movement.

3. The Capillaries, 'fhese are microscopic vessels and they con-
sist of a single layer of endothelial cells between which are scattered
small openings through which white blood corpuscles can pass into
the tissues. The exchange between the blood and the tissue fluid of
dissolved gases, nutritive material and waste products takes place
through the capillary endothelium.

THE MEDIASTINUM

The mediastinum is the space between the two pleural cavities

THE HEART

I2I

and it contains the pericardium, the heart, the great vessels, the
oesophagus, the trachea, the thoracic duct, the thymus gland and
lymph nodes.

It is divided into superior and inferior parts, and the latter is
further divided into anterior, middle and posterior portions.

The superior mediastinum lies between the manubrium of the
sternum in front and the upper four thoracic vertebrae behind. It
contains the arch of the aorta and its branches, the innominate veins
and upper half of the superior vena cava, the trachea, the oesophagus
and the thoracic duct.

The anterior mediastinum lies between the pericardium behind and
the sternum in front.

The middle mediastinum contains the pericardium, the heart, the
roots of the great vessels,, the roots of the lungs, the bifurcation of the
trachea and the main bronchi.

The posterior mediastinum lies behind the pericardium and contains
the oesophagus, the descending thoracic aorta, the thoracic duct
and lymph nodes.

THE HEART

The heart is a hollow musclar organ of conical shape lying in the
mediastinum (see p. 120) in a fibrous sac, the pericardium. It consists

Pulmonary

Direction of blood-flow

Venous blood returned to heart
Oxygenated bhod from lungs I t

Fig. 10.3 Circulation of blood through the heart.

122

THE CIRCULATORY SYSTEM

of right and left halves which are completely separate from each
other. The right side drives the blood to the lungs and is less powerful
than the left side which is the pump for the systemic circulation and
has to drive the blood to the brain, the limbs, the alimentary canal,
the kidneys, etc. Each half of the heart consists of two/:hambers
which communicate through a valve; thus the right side of the heart
consists of the right atrium into which blood flows from the systemic
veins of the body (the superior and inferior venae cavae) and the
right ventricle from which the pulmonary artery passes to the lungs.
Between the two chambers of the right side is the tricuspid valve sos.
named because it is composed of three cusps or flaps. The left side
of the heart consists of the left atrium into which the pulmonary veins,
carrying blood from the lungs, flow and the very powerful left ven-
tricle from which the aorta conducts blood to the entire body except
for that blood which goes to the lungs for the purposes of respiration.
Between the left atrium and left ventricle is the mitral valve, so called
because it consists of two cusps which are supposed to resemble a
bishop’s mitre.

Orifices of coronary arteries

Chordae
tendineae
of mitral
valve

Aorta cut
open and
flattened
out

Aortic

valve

Papillary

muscle

Fig. 10.4 The aorta opened to show valve cusps.

The heart is so placed that the right atrium is on the right side,
the right ventricle is in front, the left ventricle is on the left side and
the left atrium is behind. The pulmonary veins which discharge
oxygenated blood into the left atrium therefore enter the back of the
heart. The aorta leaves the left ventricle and runs upwards and to

THE HEART

1 83

ihe right but is concealed at its commencement, when viewed from
the front, by the main pulmonary artery which comes from the
most anterior chamber of the heart, the right ventricle. The superior
and inferior venae cavae, by which the systemic venous blood is
returned to the heart, enter the right atrium from above and below

L Subclavian
Artery

Middle

R. Lung

L. Innominate
— ^ Vein

Pulmonary

Artery

Lower Lobe
L Lung

R. Ventricle

Fig. 10.5 I’lie lungs, heart and great vessels.

respectively and form with the atrium the right border of the
mediastinum.

The heart receives its own blood supply from the coronary arteries
which leave the aorta soon after its commencement; blood is
returned from the myocardium to the right atrium by the coronary
sinus.

Structure of the Heart. The muscular wall of the heart is known
as the myocardium and it is composed of involuntary muscle having
certain microscopical characteristics which difl'erentiate it from all
other involuntary muscle. The epithelial layer which lines this is the
endocardium and the fibrous sac which encloses the heart is called the
pericardium. The pericardium is lined by a serous membrane (see
p. 12) which is continued over the surface of the heart. These serous
layers (the parietal and visceral respectively) are comparable in

124 CIRCULATORY SYSTEM

arrangement and function with the pleura (p. 152) and the periton-
eum (p. 184) and like them they allow the structures which they
cover to move over each other without friction.

The atria are relatively thin walled because they only have to
pump blood into the ventricles; each has a small pouch ^called an
auricle* projecting from it. The atria are separated from each other
by the interatrial septum and the ventricles are separated by the inter-
ventricular septum.

The cusps of the mitral and tricuspid valves arc derived from the
endocardium and their free margins are connected by tendinous cords
to the papillary muscles which project from the ventricular walls.
There are valves also at the origins of the pulmonary artery and
aorta; they consist of three flaps of half-moon shape. The purpose of
all these valves is to prevent the flow of blood in the reverse direction.

The Cardiac Cycle

The heart beats automatically although it is under the control of
the nervous system for it receives innervation from the vagus nerve
(p. 246) and the sympathetic nervous system (p. 252). The heart
rate is slowed by stimulation of the former and accelerated by
stimulation of the latter. The pumping action of the heart consists of
a contraction or systole and a relaxation or diastole. Both atria
contract simultaneously, driving their contents into the relaxed
ventricles during ventricular diastole, the ventricles then simul-
taneously go into systole whereas the atria go into diastole and blood
flows into them from the venae cavae to be discharged into the
ventricles during the next atrial systole. The usual rate of beatintr of
the heart is^To/per minute bu t it increases during exercise or excite-
ment and in various abnormal conditions.

The rhythm of the cardiac cycle results from the co-ordination of
the myocardial contractions achieved by specialized nervous tissue,
jh^he cardiac impulse starts in the pacemaker or sino-atrial node situated
in the wall of the right atrium, it spreads to the atrioventricular node
which lies in the upper part of the interventricular septum and is
conducted from this point by the bundle of His to all parts of the
ventricles. The cardiac cycle is accompanied by sounds which can
be detected by the stethoscope and by electrical changes which can
be recorded by the electrocardiograph.

* Formerly the atria were called the auricles and the auricles were known as the
auricular appendages.

CIRG\ 3 L\T 10 N OY THt

The Radiographic Appearances of the Heart

. (see Fig. 1 1.9)

In the anterior projection with the cassette at a distance of 6 feet
from the X-ray tube the maximum transverse diameter of the
heart shadow during inspiration in a normal subject does not usually
exceed 50 per cent of the maximum internal transverse diameter of
the chest. The right border of the heart and great vessels is made up
of the superior vena cava, the right atrium and a short length of the
inferior vena cava. The left border shows a prominence known as
the aortic knuckle produced by the arch of the aorta. Below this the
left heart border is composed of the left side of the main pulmonary
artery, a short segment due to the left auricle and finally a longer
segment produced by the left ventricle. The inferior border of the
heart merges with the diaphragmatic shadow.

Examination in oblique projections is particularly useful in
assessing the size of the left atrium and both ventricles. For the left
atrium the right anterior oblique projection is used (i.e. right breast
towards cassette or fluoroscopic screen) and the patient is given
barium cream to swallow. The oesophagus shows impressions
caused by the aortic arch, the left bronchus and pulmonary artery
and below this is a long sifftooth curving impression due to the left
atrium. In the left anterior oblique position the left ventricle is
seen nearest the vertebral column and the right ventricle is seen
anteriorly.

The heart may be investigated in the X-ray department by plain
radiography, by fluoroscopy, by cardiac catheterization (for the
purpose of taking samples of blood and measuring the pressure in
various chambers) and by angiocardiography (the injection of an
opaque medium into the heart followed by serial radiographs to
demonstrate the opacified heart chambers).

THE CIRCULATION OF THE BLOOD

It will be recalled that the circulatory system consists of the
systemic, the pulmonary and the portal circulations.

The systemic circulation is concerned with the passage round
the body of the blood which the heart receives from the pulmonary
circulation. The route taken by the blood is from the left ventricle
to the aorta, its branches and their ramifications throughout the
body. The blood thus reaches the capillaries and after traversing
them it returns to the heart by the venules, the veins and the

126

THE CIRCULATORY SYSTEM

Fig. 10.6 Diagram of the circulation.

superior and inferior venae cavae which drain into the right atrium.

The object of the pulmonary circulation is to carry ‘impure’
blood (i.e. blood which is saturated with carbon dioxide and defi-
cient in oxygen) to the lungs and to return the ‘purified’ blood to
the heart. The blood leaves the right ventricle through the pul-
monary artery which distributes it to the lungs. As it passes through
the capillaries of the lungs the blood gives up carbon dioxide and
acquires more oxygen and is returned to the left atrium by the
pulmonary veins.

Portal circulation. Reference to Fig. io.6 shows that the venous
blood returning from the stomach and intestines does not pass
directly to the inferior vena cava but, having traversed the capil-
laries of the bowel, it is collected into a vein called the portal vein
which takes it to the liver. The blood then passes through the
capillaries of the liver and enters the tributaries of the hepatic
(liver) veins which join the inferior vena cava. This system is
considered further on p. 138.

IHE CIRCULATORY SYSTEM

127

Trachea

^sophagus

/ Left internal

jugular vein

Right

Innominate vein

Innominate

artery

Superior
vena cava

Right

pulmonary

artery

Right
pulmonary
veins

Right auricle

Inferior
vena cava

Right coronary
artery

Left

subclavian

artery

Left

subclavian

vein

Left

Innominate

vein

Left common
carotid artery

Aortic arch

Left and right
putmoi^ry arteries

eft

pulmonary

veins

Left auricle
Pulmonary trunk

Left coronary
artery

OEsophagus

Descending

thoracic

aorta

Fig 107 Anterior surface of the heart and great vessels

128

THE CIRCULATORY SYSTEM

The Bronchial and Hepatic Arteries

The lungs do not depend for their nutrition on the venous blood
brought to them by the pulmonary arteries nor is the liver dependent
on the portal blood for its nutrition. There are bronchial arteries
(p. 129) which supply the lungs and hepatic arteries which supply
the liver with arterial blood.

Trachea

Innominate

artery

Right

bronchus

OEsophagus

Left common
carotid artery

Left

subclavian

artery

Left

bronchus

Descending

aorta

Aorta piercing
the diaphragm

Fig. 10.8 The aorta in the thorax.

The Great Vessels of the Thorax

When the heart and great vessels are seen from the front the
superior vena cava lies on the right side of the aorta and the pulmonary
artery on the left.

The superior vena cava is formed by the junction of the two
innominate veins each of which results from the union of the sub-clavian

THE ARTERIES OF THE THORAX

129

and internal jugular veins of its own side. The right innomin-
ate vein runs in the same direction as the vena cava but the left
crosses from left to right above the aortic arch, anterior to the left
common carotid and innominate arteries and the trachea. The
inferior vena cava enters the thorax through the diaphragm and
runs a very short course before reaching the right atrium.

The aorta is the largest artery in the body and from its origin in
the left ventricle it passes upwards, forwards and to the right and
is known in this part of its course as the ascending aorta. Then as the
aortic arch it curves backwards and to the left to reach the level of
the body of the fourth thoracic vertebra where as the descending aorta
it runs down behind the pericardium and to the left of the oesophagus
and vertebrae until it pierces the diaphragm where it lies anterior to
the vertebral column. On the left are the pleura and lung and on
the right are the azygos vein and thoracic duct.

The only branches of the ascending aorta are the coronary
arteries which supply the myocardium.

The arch of the aorta gives off three branches, (i) the innominate
artery which passes to the right side of the trachea and then divides
into the right common carotid and right subclavian arteries (there is no
innominate artery on the left side). (2) the left common carotid artery
copies directly off the aortic arch immediately to the left of the
innominate artery and ascends into the neck on the left side of the
trachea. (3) The left subclavian artery arises from the arch behind
the left common carotid artery and ascends on the left of the trachea
to the root of the neck where it turns to enter the left axilla.

T’he descending aorta gives off the bronchial arteries which
supply the lungs. Branches arc also given to the oesophagus, the
pericardium and the intercostal spaces.

The pulmonary artery, which,, the student will remember, carries
de-oxygenated blood to the lungs, arises from the right ventricle and
passes upwards, liackwards and to the left b<5ing at first in front of the
ascending aorta, then to the left of it, anid finally it divides in the
concavity of the aortic arch into^,the right and left pulmonary
arteries. The right pulmonary artery luns behind the ascending aorta
and superior vena cava and in front of the oesophagus to reach the
hilum of the right lung. The left pulmonary artery runs in front of the
descending thoracic aorta to reach the hilum of the left lung.

The pulmonary veins, of which there are two on each side,
come from the lungs and enter the left atrium on the posterior
aspect of the heart. Unlike the veins of the systemic circulation they
carry oxygenated blood.

THE CIRCULATORY SYSTEM

130

The azygos vein is not strictly one of the great vessels but it is
convenient to describe it here. It begins in the abdomen at the level
of the first lumbar vertebra and is connected at its origin with the
inferior vena cava. It runs upwards in front of the vertebral bodies,
passing through the aortic opening in the diaphragm; it then lies on
the right of the descending aorta and behind the oesoph^fgus until
it reaches the upper part of the root of the right lung where it
arches forwards and terminates in the superior vena cava. The
azygos vein receives tributaries from the lumbar region, the posterior
thoracic wall, the oesophagus, etc.

Arteries of the Abdomen

'^he abdominal aorta enters the abdomen through the aortic
orifice in the diaphragm opposite the lower border of the twelfth
thoracic vertebra and descends in front of tjie vertebral column on
the left side of the inferior vena cava to the body of the fourth
lumbar vertebra where it divides into the two conjmon iliac arteries.
It is crossed anteriorly by the left renal vein, the pancreas and the
root of the mesentery.

The branches of the abdominal aorta are divided into the visceral

Phrenic Artery

R. Common
lilac Artery

R. External
Iliac Artery
and Vein

Superior

Mesenteric Aitery

T" Inferior

A Mesenteric Artery

L. Internal Iliac
Artery and Vein

Fig. 10.9 Diagram of the abdominal aorta and inferior vena cava
with some of the larger branches of each.

ARTERIES OF THE HEAD AND NECK I3I

which supply the abdominal organs and the parietal which supply
the abdominal wall. They are of considerable radiographic interest
as they are frequently demonstrated in the examination known as
aortography. The chief visceral branches are:

(1) the coeliac axis which supplies the liver, stomach, pancreas
and spleen.

(2) the superior mesenteric which supplies the small intestine.

(3) the right and left renal arteries which supply the kidneys.

(4) the inferior mesenteric which supplies the large intestine.

(5) the testicular in the male and the ovarian in the female which
supply the sex glands (gonads).

The chief parietal branches are the five paired lumbar arteries
which pass laterally on each side.

The common iliac arteries are the terminal branches of the aorta and
run downwards and laterally for a short distance in front of the last
lumbar vertebra before dividing into the internal and external iliac
arteries.

The internal iliac artery descends into the pelvis to supply the
pelvic organs such as the rectum, bladder and uterus and other
branches supply the buttocks

The external iliac artery runs downwards and laterally along the
medial border of the psoas muscle and passes beneath the inguinal
ligament to enter the thigh.

Arteries of the Head and Neck

The head and neck are supplied with arterial blood by the
common carotid and vertebral arteries. The common carotid arteries
divide into the external and internal carotid arteries. The external
supplies the face, scalp, neck and meninges, the internal carotid
artery supplies the anterior part of the brain, and the vertebral,
which is a branch of the sul^lavian artery, supplies the posterior
part. There is considerable variation in the amount of the brain
which is supplied by each vessel because of the free mingling of
blood which occurs in the Circle of Willis (see below).

The middle meningeal artery arises from the internal maxillary artery,
a branch of the external carotid, and enters the skull through the
foramen spinosum of the sphenoidal bone (see p. 44). It runs
laterally and forwards in a groove on the squamous part of the
temporal bone and divides into an anterior and a posterior branch
(see p. 54).

132

THE CIRCULATORY SYSTEM

, The common carotid arteries differ in their mode of origin, the right
arising from the innominate artery and the left directly from the
aortic arch. These vessels run up the neck on either side of the
trachea and thyroid gland, dividing into external and internal
branches at the level of the upper border of the thyroid c^tilage.

The internal carotid artery continues up to the base of the skull,
passing through the carotid canal in the petrous portion of the
temporal bone, it enters the middle cranial fossa by emerging
through the upper part of the foramen lacerum (see p. 44) and at the
base of the brain it divides into anterior and middle cerebral arteries.
Between the anterior cerebral artery and its fellow of the opposite
side is the anterior communicating artery.

The vertebral artery arises from the subclavian and ascends through
the foramina in the transverse processes of the upper six cervical
vertebrae to enter the skull through tlie foramen magnum. At the
lower border of the pons the vertebral arteries of both sides join to
form the basilar artery which ascends in the mitllinc to the upper
border of the pons where it divides into the two posterior cerebral
arteries. These vessels supply the posterior part of the cerebrum and
are connected to the internal carotid arteries by the posterior com-
municating arteries. The basilar artery also gives branches which
supply the cerebellum and pons.

The circle of Willis. The blood supply of the brain is to a large
extent safeguarded by the free communication which exists be-
tween the vessels derived from the internal carotid and those

> P *

Anterior Cerebral
Artery

Internal Carotid
Artery

Middle Cerebral
Artery

Posterior
Communicating
Artery

Posterior Cerebral
Artery

Basilar Artery
Vertebral Artery

Fig. 10.10 The arterial circle (of Willis) at the base of the brain.

The arrows indicate the direction of the flow of the blood.

Anterior Communicating
Artery

ARTERIES OF THE UPPER LIMB I33

derived from the vertebral arteries. This communication takes the
form of a ring of arteries round the base of the brain ; it consists
anteriorly of the anterior cerebral and the anterior communicating
arteries and posteriorly of the posterior cerebral arteries, the two
terminal branches of the basilar artery (itself formed by the union
of the two vertebral arteries), which are connected to the internal
carotid vessels by the posterior communicating arteries.

Anterior

cerebral

artery

Middle

cerebral

artery

Posterior

cerebral

artery

Internal

carotid

artery

Fig. 1 0.1 1 Carotid arteriogram showing the internal carotid artery
and its branches.

Arteries of the Upper Limb

The origins of the subclavian arteries have already been described
(p. 129). Each passes laterally over the first rib to gain the axilla
where it becomes the axillary artery. This artery crosses the axilla
and then, renamed the brachial artery^ it runs down the inner side of
the upper arm to divide in front of the elbow joint into the radial
and ulnar arteries \ these run down the radial and ulnar sides of the
forearm respectively and communicate with each other in the palm
of the hand forming the palmar arches from which the digital
branches run to the fingers.

Various branches to neighbouring structures, such as the nutrient
arteries to the bones, and branches to the muscles, joints and sub-
cutaneous tissue are given off by these vessels during their course.

*34

THE CIRCULATORY SYSTEM

Left common
carotid artery

^ teft subclavian
* artery

Arch of aorta

. Descending
thoracic
aorta

Common
iliac artery

Internal
iliac artery

External
iliac artery

- Femoral
artery

Fig. 10.13 The systemic arteries of the body.

135

ARTERIES OF THE LOWER LIMB

continuation of the external iliac artery. It is at first superficial so
that beneath the inguinal ligament it can be palpated but it then
passes into the muscular tunnel known as the adductor (Hunter’s)
canal (p. 1 1 5) and ends by piercing the adductor muscle group to
enter the popliteal fossa.jThe largest branch of the femoral artery is
the profunda femoris whim is at first lateral and then posterior to the
femoral artery and it supplies many of the muscles of the thigh and
has connections with the popliteal artery.

The popliteal artery is the direct continuation of the femoral and
crosses the popliteal space, at the lower end of which it divides into
the anterior and posterior tibial arteries. The former runs down the
front of the leg to gain the dorsum of the foot where it is called the
dorsalis pedis artery^ and the latter descends behind the tibia to reach
the sole of the foot where it divides into the medial and lateral plantar
arteries. The lateral plantar artery anastomoses with the terminal

THE VEINS

136

branch of the dorsalis pedis artery which pierces the tissues between
the first and second metatarsal bones to reach the sole of the foot.
The arch so formed gives off branches which supply the toes. A
large branch of the posterior libial artery, the peroneal^ runs close to
the fibula in the lateral part of the calf. ,

As in the upper limb these arteries supply branches to neighbour-
ing structures and around the main joints there are communications
between the branches arising from the main vessels above the joint
with others arising from below the joint; these anastomoses, as they
are called, play an important part in the maintenance of the circula-
tion in the limb if the main vessels become obliterated by disease.

Veins of the Head and Neck

The veins of the brain drain into large vessels in tlic dura mater-
known as venous sinuses. One of these, the sagittal or superior longi-
tudinal sinus, runs backwards in the mid plane beneath the sagittal
suture; all the venous sinuses drain into the ti^ansverse sinuses of
which there is one on each side and these often produce a groove
which can be seen in radiographs of the occipital bone (p. 56) .
The transverse sinuses curve laterally and downwards to the jugular
foramina in the posterior fossa through which they leave the skull to
become the internal jugular veins.

The internal jugular veins are deeply placed in the neck and each
runs from the jugular foramen to the subclavian vein with which it
unites to form the innominate vein. During their course they are
closely related to the carotid arteries.

There are also some superficial veins in the neck which drain into
the subclavian veins.

Veins of the Upper Limb

The deep veins of the upper limb accompany the radial, ulnar and
brachial arteries and join the axillary vein.

There are several large superficial veins in the upper limb. The
cephalic vein arises on the lateral (radial) side of the hand and
ascends on the lateral side of the forearm and arm to join the
axillary vein. The basilic vein runs from the medial (ulnar) side of
the hand up the medial side of the forearm and arm to pierce the
deep fascia and join the deep veins flowing with the brachial artery
to form the axillary vein. In front of the elbow the cephalic and
b2Lsilic veins communicate with each other and with other superficial
veins by the median cubital vein — a vessel which is commonly used
for administering intravenous injections.

THE VEINS

137

The axillary vein crosses the axilla to become the subclavian vein^
which runs across the first rib to be joined by the internal jugular
vein to form the innominate vein. The left subclavian vein is joined
by the thoracic duct (see p. 158) and the right receives the right
lymph duct.

Veins of the Lower Limb

The deep veins consist of the anterior and posterior tibial which

K

THE VEINS

138

unite to form the popliteal vein which ascends through the popliteal
space to the adductor canal and, running beside the femoral artery
as the femoral vein reaches the inguinal ligament behind which it
passes to become the external iliac vein.

The superficial veins consist of the long saphenous vein which runs
from the foot up the inner side of the limb to join the femoral just
below the inguinal ligament and the short saphenous vein which ascends
the back of the calf to join the popliteal vein behind the knee.

Veins of the Abdomen

The external iliac vein is the continuation of the femoral and it
ascends on the inner side of the external iliac artery to join with
the internal iliac vein and form the common iliac vein. The two
common iliac veins unite in front of the fifth lumbar vertebra to
form the inferior vena cava (see Fig. 10.9) which ascends in front of
the vertebral column, lying on the right of the abdominal aorta. It
then passes behind the liver and reaches the diaphragm through
which it passes at the level of the eighth thoracic vertebra. Its
subsequent course has already been described (see p. 129). Among
its tributaries are the renal veins (from the kidneys), the right
suprarenal vein, the hepatic veins (from the liver), the right testi-
cular and the lumbar veins.

The azygos vein has been described earlier in this chapter (p. 130).

The portal vein (see p. 126) is formed by the union of the superior
mesenteric and splenic veins. The Superior mesenteric vein drains the
small intestine and the splenic vein drains the spleen, the lower part
of the oesophagus and the stomach and it receives the inferior
mesenteric vein which drains the large intestine. The portal vein is
about 3 inches (7.5 centimetres) long and as it runs to the liver it is
closely related to the hepatic artery and the common bile duct. In
the liver the vein branches into smaller and smaller vessels and
ultimately the blood reaches the capillaries and blood spaces known
as sinusoids. The portal circulation thus starts in the capillaries of
the bowel and spleen and ends in the capillaries and sinusoids of the
liver. After passing through the liver the portal blood returns in the
hepatic veins and inferior vena cava to the heart.

The anal region and the lower part of the oesophagus are drained
also by the vena caval system and as communications between the
portal and caval systems occur at these sites, varicosities may develop
if there is obstruction to the flow of blood in the portal vein as may
occur in certain types of liver disease.

THE BLOOD

*39

Inhrior vent cave
rece/ving htpMtIc veins

Outline of
liver

Portal vein

Superior mesenteric vein

Ascending colon

Spleen

Inferior mesenteric vein

Descending

colon

Fig, 10.15 Ditgram of the portal circulation.

The portal system may be demonstrated by the injection of an
opaque medium into the spleen and this procedure is often used to
demonstrate the presence of varicosities in the lower oesophagus.

THE CIRCULATION OF THE BLOOD IN THE FOETUS

The foetus receives its nutrition and breathes by the placenta to
which its aorta is connected by the umbilical artery and its inferior
vena cava by the umbilical veins. Partially de-oxygenated blood is
carried by the former and freshly oxygenated blood by the latter.

The lungs need relatively little blood before they are used for
respiration (i.e before birth), so blood is short-circuited from the
pulmonary artery into the aorta by the ductus arteriosus^ and from the
right side of the heart to the left by an aperture {the foramen ovale)
between the two atria. At birth breathing is established and this
results in the closing of these two communications.

THE BLOOD

Functions of Blood

Blood is a fluid substance which carries nutritive material to the

THE BLOOD

140

tissues and removes waste products. It carries oxygen from the lungs
and receives carbon dioxide from the tissues in exchange. Varying
amounts of heat are produced in different organs as a result of
processes occurring within them and it is one of the functions of
blood to disperse this heat around the body. Certain gla^j^ds — the
ductless glands — discharge their secretions (hormones) directly into
the blood stream and the blood then distributes these secretions
round the body. The blood also plays an essential part in the
defence of the body against bacterial invasion.

Composition of Blood

An adult has about 10 pints (5 litres) of blood and analysis shows
that blood consists of approximately equal quantities of a liquid part
called p/asma and solid elements called ce//s or corpuscles. The cells are

Fig. 10.16 The cells of the blood.

composed of red blood corpuscles, white blood corpuscles and
platelets.

»

The Red Blood Corpuscles. These are the most numerous of
the blood cells, there being usually about 5,000,000 per cubic
millimetre. They are bi-concave circular discs and measure about
1/3200 inch (about 8|j) in diameter. Mature red corpuscles contain
no nucleus. They owe their red colour to the haemoglobin which
they contain.

Haemoglobin is a complex substance consisting of protein and an
iron-containing pigment and it has a very strong affinity for oxygen,

THE BLOOD

141

with which it combines to form oxyhaemoglobin which readily
gives up its oxygen to the tissues. The carbon dioxide which the
blood receives in exchange for its oxygen is principally carried in
solution in the plasma. Normally the blood is said to contain 100 per
cent haemoglobin and in a simple iron deficiency anaemia it will
contain considerably less than this.

The red blood corpuscles arc manufactured in the red bone
marrow, which in the infant occupies all the marrow spaces but in
the adult occurs in the vertebrae, skull, ribs and pelvis. The deve-
loping red cell is nucleated until maturity is reached, that is just
before it is released into the circulation.

Certain substances are required for the normal development of
red blood cells and the haemoglobin which they contain. These
include an adequacy of protein, vitamins B and C, iron and traces
of other salts in the diet and the presence of a sufficiency of a sub-
stance known as the anii-anaemic factor which is formed by the com-
bination of the intrinsic factor, a secretion of the stomach (p. 187), with
the extrinsic factor, a constituent of the food known as vitamin 812-
I’he anti-anaemic factor is stored in the liver and deficiency of it
results in pernicious anaemia.

The average life of the<?red cell is about 4 months and at the end
of this time the cells are destroyed by the spleen; the iron is used
again for the production of haemoglobin, but the pigment is con-
verted into bile pigment by the liver.

The White Blood Corpuscles (or Leucocytes). These cells are
bigger but much less numerous than the red cells. There are usually
about 8000 per cubic millimetre and the chief varieties found are the
polymorphonuclear cells, the lymphocytes and the large mono-
nuclear cells.

The white blood cells play an important part in the defence of the
body against bacterial invasion; they do this by their power of
neutralizing the toxins of the organisms and by phagocytosis.
Phagocytosis is the ability of certain cells to ingest foreign matter in
the same way as the amoeba takes in food (Fig. 2.3) and is the
outstanding feature of the polymorphonuclear leucocytes.

The polymorphonuclear leucocytes have, as their name suggests,
nuclei of variable and irregular shapes. They constitute about 70
per cent of the white cells and are capable of amoeboid movement.
Their chief functions are to attack and ingest bacteria and to
ingest (also by phagocytosis) dead and injured material. Many
leucocytes may be killed in their onslaught on invading bacteria and

142 SOME EFFECTS OF RADIATION ON THE BLOOD

the dead cells with surrounding necrotic material constitute what is
known as pus.

The lymphocytes comprise about 25 per cent of the white blood
cells. They have a large nucleus and although they are not phago-
cytic they play a definite role in the defences of the body. They are
made chiefly in the germ centres of the lymph nodes and spleen.

The platelets are about one-third of the diameter of the red cells and
number about 250,000 per cubic millimetre. They are concerned with
the clotting of blood and are manufactured in the bone marrow.

The average length of life of the platelets and lymphocytes is very
short, the latter surviving less than one day in the blood stream. The
polymorphonuclear cells survive about 30 days.

The blood plasma is a straw coloured, slightly alkaline fluid
containing water, protein, salts and sugar. Of the proteins fibrinogen
is the one concerned with clotting and when this is removed serum
is left; the protein of the serum carries antibodies and special sera
are used in the prevention and treatment of diseaSe.

BLOOD-

CELLS-

Red

White

Platelets

PLASMA-\

Fibrinogen
(dot protein)
Salts, sugars,
Fats, etc
Water

Other proteins

These

““ constitute

BLOOD CLOT

These

constitute

SERUM

y/The clotting of blood is the mechanism by which blood loss is
•minimized at the site of wounds. It consists in the conversion of
fibrinogen into fibrin, a web-like substance which fills the wound
and plugs it. Red blood cells become entangled in the meshes of the
fibrin plug, which expresses serum as it contracts and forms a firm
clot. The conversion of fibrinogen into fibrin is a result of an enzyme
liberated from the platelets and the process can be prevented by
adding citrates or heparin to the blood. Many technical procedures,
such as cardiac catheterization for example, could not be performed
if it were not possible thus to prevent blood from clotting.

SOME EFFECTS OF RADIATION ON THE BLOOD

Long continued irradiation of the body by small doses of X-rays,
such as could be received by a radiographer who persistently

THE BLOOD

H3

ignored safety precautions, may cause changes in the blood; these
result from the effects of radiation on the cells in the bone marrow
^nd germ centres of the lymph nodes which form the red and white
blood corpuscles and the platelets. One of the effects on the blood
of such exposure may be depression of the white or red cell count
or both. Sometimes the lymphocytes are not depressed to the same
extent as the remainder of the white corpuscles owing to a com-
pensatory increase in the production of lymphocytes by the germ
centres of the lymph nodes. If exposure continues for a sufficiently
long period the incidence of leukaemia, a rare malignant disease of
the blood, is probably increased.

In radiotherapy if relatively large areas of the body are irradiated
fairly heavily much more pronounced changes in the blood may be
observed. In such a case there may be depression of all the cellular
elements of the blood, the red and white cells and the platelets.
The most severe manifestations of radiation effects on the blood
have been seen after exposure to explosions of atomic bombs ; in
such cases the depression of the white cells results in diminished
resistance to bacterial infections, the depression of the platelets
disturbs the clotting mechanism and results in liability to haem-
orrhage, and the diminution of the red blood count results in
anaemia. Death may resufi from any of these effects.

Pathological Considerations

The development of the heart is complex and many errors may
occur during the process. Patients suffering from developmental
abnormalities of the heart are said to have congenital heart disease.
C'ertain of the complex anomalies result in the mixing of arteries and
venous blood and the individual is cyanosed or ‘blue’.

There are many forms acquired heart disease also. Amongst these
are inflammatory conditions of the endocardium, e.g. rheumatic
disease of the valves usually of the mitral, sometimes of the aortic
valve and the affected valves may become constricted and incom-
petent.

Arteries may be affected by a degenerative condition called
atheroma which may lead to their becoming blocked {thrombosis).

Diminution in the supply of arterial blood to muscles may result
in cramping pain during exercise, in the legs this is called inter-
mittent claudication (literally ‘intermittent stopping’). More severe
impairment of blood supply to a part may result in death of tissue,
i.e. gangrene. If the coronary arteries become thrombosed severe

144 PATHOLOGICAL CONSIDERATIONS

incapacity or death may follow as part of the heart wall may die and
be replaced by fibrous tissue {infarction ) .

A collateral circulation offers an alternative route to the passage of
blood along a main artery. This is because not all arterial branches
end in capillaries, some unite with each other forming anastomoses.
If a main artery becomes blocked over a short distance the collateral
vessels constituting the anastomotic circulation may carry enough
blood to maintain a circuriation through the main vessel beyond the
block thus ensuring, for instance, the survival of a limb.

Loss of blood is called haemorrhage. Deficiency of haemoglobin is
anaemia. A diminution in the white cell count is called leucopenia and
an increase in the count is a leucocytosis and usually accompanies
infections. Leukaemia is a malignant proliferation of the tissue in the
bone marrow which forms white blood corpuscles.

The Respiratory System

THE PHARTJVX

The nose and nasal cavity have already been described (p. 48),
The posterior nares connect the nasal cavity to the nasopharynx^
which is that part of the pharynx lying above the soft palate. The
nasopharynx also communicates with the middle ears through the
auditory {Eustachian) tubes which open into its lateral walls; collec-
tions of lymphoid tissue known as adenoids may be present on its
posterior wall.

Inhaled air passes from the nasopharynx to the oropharynx which is
situated behind the mouth and extends from the soft palate above
to the tip of the epiglottis below; it is common to both the ali-
mentary and respiratory systems. This part and the lowest part, the
laryngopharynx, are described with the alimentary system (see p. 1 79).

THE LARYNX

The larynx is the organ of voice production as well as being an air
passage. It lies between the root of the tongue and the trachea, in
front of the third, fourth, fifth and sixth cervical vertebrae in the
adult. The skeleton of the larynx is cartilaginous and within it are
the vocal cords. The hyoid bone (p. 52) lies above the larynx, to
which it is attached by the thyro-hyoid membrane, and below the
tongue. It is not part of the larynx but is closely related to it.

There are three single laryngeal cartilages, the epiglottis, the
thyroid and the cricoid, and several paired cartilages of which the
most important are the arytenoid cartilages. These and other
smaller laryngeal cartilages may be seen in radiographs of the neck
if calcium is laid down in them.

The epiglottis is a leaf-shaped cartilage which projects upwards
behind the hyoid bone and the base of the tongue and in front of the
opening of the larynx; it prevents food from entering the larynx
during swallowing. The epiglottis is covered by mucous membrane

145

146

THE RESPIRATORY SYSTEM

Corpus calldium

Sup. sagittal smus

Optic
chiasma ,

hypophysis
cerebri '

\ Calcarine
sulcus

)ethmoidal ^
recess

up. concha "

Sphenoidal

uLf- Basilar
artery

Pharynco-

tympanic

tube

Soft palate

Lingual tonsil

Hyoid ‘
Epi^ottis <
Vestibular fold •

Vocal fold

Fig. 1 1. 1 A sagittal section through head and neck.

THE LARYNX

H7

Lesser cornu

Greater cornu of hyoid
bone

Thyrohyoid membrane
Superior cornu

Inferior cornu
Cricotracheal ligament

Epiglottis

Body of hyoid bone

Thyroid cartilage

Cricothyroid ligament
Cricoid cartilage

1st, 2nd and 3rd
tracheal rings

Fig. 1 1. a The cartilages of the larynx.

Third cervical
vertebra

Cricoid cartilage

Thyroid cartilage
Cricothyroid muscle

Thyroid gland

Trachea

Fig. 1 1.3 The larynx, the thyroid gland and the cervical portion of the trachea.

THE RESPIRATORY SYSTEM

148

which is reflected from its anterior surface to the base of the tongue;
and on either side of this fold is a recess known as the vallecula.

The thyroid cartilage is the largest and consists of two laminae
which fuse in the midline to form the prominence known as the
Adam’s apple. At the posterior borders of the laminae the superior
and inferior horns project.

The cricoid is smaller but stronger and is described as being like a
signet-ring in shape. The expanded portion lies posteriorly and the
cartilage completely encircles the larynx.

The arytenoid cartilages are two pyramid-shaped structures on the
upper surface of the posterior part of the cricoid cartilage. They
partly occupy the space between the two laminae of the thyroid
cartilage and form the posterior attachments of the vocal cords.

The vocal cords consist of one pair of false cords (or ventricular folds)

Fig. 1 1 .4 Diagrammatic coronal section of the larynx seen from behind.

THE LARYNX

149

which separate the vestibule of the larynx from the ventricle \ and one
pair of true cords (or vocal folds) which separate the ventricular and
subglottic portions of the larynx. The false vocal^ cords do not play
any part in voice production but augment the action of the epi-
glottis in preventing the entry of food into the larynx during swallow-
ing. The true vocal cords run from the arytenoid cartilages to the
inner aspect of the anterior part of the thyroid laminae and they can
be tightened or loosened by muscles attached to the arytenoid
cartilages. The fissure between the true cords is the glottis and the

Fig. 1 1 .5 The larynx, trachea and main bronchi — anterior aspect.

passage of air through it when the cords are tense results in the
production of sounds, i.e. phonation.

The nasal cavities, the larynx (except for the vocal cords), the
trachea and the bronchi are lined by ciliated columnar epithelium
(p. 10).

150 THE RESPIRATORY SYSTEM

THE TRACHEA

The trachea or windpipe is about 4^ inches (lo-i i centimetres) in
length and i inch (2.5 centimetres) in diameter. It extends from the
sixth cervical vertebra above to the fifth thoracic vertebra below,
where it divides into the two main bronchi. It consists of fibrous
tissue and involuntary muscle strengthened by C-shaped rings of
cartilage which surround its front and sides, but are deficient
posteriorly. It is lined by ciliated columnar epithelium. The trachea
runs from the neck to the superior mediastinum so it has a cervical
and a thoracic portion.

Relations of the Cervical Part of the Trachea

The isthmus of the thyroid gland and the infrahyoid muscles are
anterior. The lobes of the thyroid gland and the common carotid
arteries are lateral. The oesophagus intervenes between the trachea
and the vertebral column posteriorly.

Relations of the Thoracic Portion of the Trachea

Anteriorly the remains of the thymus gland, the left innominate
vein, the arch of the aorta, and the innominate and left common

Fig. 1 1 .6 Diagram showing termination of a
respiratory bronchiole.

carotid arteries intervene between the trachea and the manubrium
of the sternum. On the right side are the right lung, the right vagus
nerve and the azygos vein; on the left side is the aortic arch.

THE BRONCHI

The bronchi are formed by the division of the trachea at the level

THE LUNGS

*51

of the fifth thoracic vertebra. They diverge from each other to reach
thup roots of the lungs. The right bronchus is about i inch (2.5 centi-
metres) in length and runs a more vertical course than the left so
that inhaled foreign bodies are more likely to pass into the right
lung. This bronchus gives a branch to the upper lobe, and after being
crossed by the right pulmonary artery it divides into the middle lobe
and lower lobe bronchi. The left bronchus is about 2 inches (5 centi-
metres) in length and passes in front of the oesophagus and below
the aortic arch and it divides at the root of the lung into the upper
and lower lobe branches. The lingular bronchus arises from the
branch to the upper lobe.

The bronchi are similar in structure to the trachea; they sub-
divide in the lungs and their smallest branches are the bronchioles.
Each bronchiole terminates in an irregular sac into which numerous
alveoli or air-cells open. The pulmonary capillaries come into
intimate contact with the alveoli and the gaseous interchanges take
place through their walls.

THE LUNGS

C'

The lungs are two light, spongy and extremely elastic structures
divided into lobes by fissures into which the visceral pleura dips.
They are separated from each other by the contents of the media-
stinum. Each has an apex projecting nearly 1 inch (2.5 centimetres)
above the sternal end of the clavicle, a base resting on the diaphrag-
matic pleura and a costal surface which is related to the chest wall
and separated from it by the costal pleura. The medial surface of the
right lung is related to the right side of the heart and the vertebral
bodies; the medial surface of the left lung is related to the left side
of the heart and the arch and descending parts of the aorta. Each
medial surface is also related to the root of the lung through which
the bronchus and pulmonary vessels pass.

The right lung is divided into three lobes, the uppery middle and
lower] the horizontal fissure separates the upper from the middle lobe
and the oblique fissure separates the upper and middle lobes from
the lower. The left lung has two lobes, the upper and lower,
separated by the oblique fissure. There is no horizontal fissure and
no middle lobe on the left.

The lungs consist of air-filled portions : the bronchi, the bronchi-
oles and the alveoli, which have been mentioned above, and a
fibrous tissue framework, called the interstitial tissue, in which blood

152 THE RESPIRATORY SYSTEM

vessels run. They are completely enveloped, except for the lung
roots, by the visceral pleura (see below).

The lungs are supplied with de-oxygenated blood by the pul-
monary artery and with freshly oxygenated blood by the bronchial
arteries. The pulmonary veins return freshly oxygenated^ blood to
the left atrium whilst the bronchial veins return de-oxygenated
blood to the right atrium. The pulmonary circulation is concerned
with the gaseous interchanges which constitute respiration; the
bronchial circulation provides for the ordinary needs of the lung
tissue.

The lymphatic drainage of the lungs is considered on page 165.

Groove for r. Apex
Groove for sup. subclavian a. of king

vena cava

Pulmonary a.^

tapper

lobe

Pulmonary vs.

Cardiac impression

Transverse fissure—

Middle lobe

. Oblique fissure

Groove for azygos

V.

IL. — . Hronchus

_ Lower lolie

(iroove for
oesopliagus

. Pulmonary
ligament

/ I

Oblique fissure Base of lung

Fig. 1 1.7 The mediastinal surface of the right lung.

THE PLEURA

The walls of the thorax are lined by, and the surface of each lung

RESPIRATION

153

is covered by, a thin serous membrane called the pleura. That lining
the chest wall is called the parietal layer and that covering the lung
the visceral layer, and they are continuous with each other at the root
of the lung. Between these layers is a closed space, the pleural cavity;
this is a potential and not an actual cavity because the lungs are
distended by atmospheric pressure so that they fill the vacuum which
would otherwise exist. Thus the parietal and visceral layers of
pleura are in contact and the slightly moist surfaces glide over each
other during breathing.

Fig. 1 1.8 Horizonlal section of ihc ches! showing visceral and paiielal pleura, etc.

TJie parietal pleura may be divided into costal, diaphragmatic
and mediastinal according to its position; inferiorly it dips into the
angle between the diaphragm and the chest wall, the costodia-
phragmatic (coslophrcnic) recess, reaching the tenth rib in the
midaxillary line and the level of the twelfth spinous process
posteriorly (p. 268).

RESPIRATION

In Chapter 2 it was explained that all living cells require oxygen
for metabolism and produce carbon dioxide as an excretion. The
gaseous interchange between the tissues and the blood in the
capillaries is called tissue (or internal) respiration and the inter-
changes between the blood and air which occur in the lungs are
called pulmonary (or external) respiration.

L

154 RESPIRATORY SYSTEM

Inspired air consists of nitrogen, oxygen and a trace of carbon
dioxide. Expired air has less oxygen and more carbon dioxide and
is saturated with water vapour but the nitrogen content remains the
same as that of inspired air.

The normal adult respiratory rate is 1 6 to 1 8 breaths per minute.
The rate is controlled by the respiratory centre in the part of the brain
known as the medulla oblongata which sends nervous impulses to
the diaphragm and intercostal muscles and causes their rhythmical
contraction. The respiratory centre is specially sensitive to the
amount of carbon dioxide circulating in the blood and if the amount
rises, as for instance during exercise, the respiratory rate and depth
will increase,

The cavity of the thorax is enlarged during inspiration by depres-
sion of the diaphragm and elevation of the ribs so that air is drawn
in. During expiration the ribs return to their former positions and
the diaphragm relaxes and is consequently raised by the pressure of
the intra-abdominal organs. These factors together with the elastic
recoil of the lungs result in the expulsion of air. About 400 c.c. of
air pass in and out of the lungs with each breath during quiet
breathing and this is called the tidal volume. An additional 1500 c.c.,
the inspiratory reserve volume, can be forcibly inspired after a normal
inspiration and about the same amount, the expiratory reserve volume,
can be expelled after an ordinary breath by forced expiration.
About 1000 c.c of air always remains in the lungs after forced
expiration, it cannot be expelled by any expiratory effort and is
called the residual volume. The sum total of the tidal, inspiratory
reserve and expiratory reserve volumes is the volume which can be
made to enter and leave the lungs by the most forcible inspiration
and expiration, and this is called the vital capacity.

I'idal volume 400 c.c.

Inspiratory reserve volume . . 1500 c.c.
Expiratory reserve volume . . 1500 c.c.

TOTAL 3400 c.c. = Vital Capacity

Oxygen diffuses through the walls of the alveoli from the atmos-
pheric air into the blood where some is dissolved in the plasma but
most of the oxygen is carried in Combination with the haemoglobin
contained in the red blood cells (page 140). Oxygen is carried round
the body in this form and passes to the cells and tissues by diffusion
into the tissue fluid (see page 158). Carbon dioxide is carried from
the tissues to the lungs partly in solution and partly in chemical

RADIOGRAPHIC APPEARANCES OF THE CHEST I55

combination with salts in the blood. It diffuses through the pul-
monary capillaries and the alveolar epithelium to enter the alveoli
from which it is expelled by expiration.

The Radiographic Appearances of the Chest

The anterior projection should be studied and described in a
systematic order and the following is suggested :

1. Superficial soft tissues. The nipples of either sex and the breasts in
the female may be seen superimposed on the lower pan of the
lung fields. The sternomastoid and pectoralis major muscles may
also cast shadows.

2. Bony parts. The posterior parts of the ribs, the costotransverse
joints and the less well defined anterior parts of the ribs which, of
course, do not reach the sternum, are seen. The costal cartilages
may be calcified in which case they will be visible. The clavicles run
laterally across the upper part of each lung field. The vertebrae are
seen imperfectly and the medial borders of the scapulae may overlap
the periphery of the lung fields.

3. The diaphragm. This structure casts a dpme-shaped shadow
slightly liigher on the rightaide than the left, meeting the chest wall
at an angle known as the costo-phrenic angle or recess. Beneath
the left side air may be seen in the fundus of the stomach and on
the right side the homogeneous shadow of the liver lies beneath the
diaphragm.

4. The trachea. The transradiant shadow of the trachea can be
seen in the midline superimposed on that of the lower cervical and
upper thoracic vertebrae.

5. The mediastinal shadow. This is made up of the heart and great
vessels. The right border consists of the superior vena cava, the
right atrium and s ^metimes the inferior vena cava. The left border
shows a prominence called the aortic knuckle caused by the arch
of the aorta; below this the left margin of the pulmonary trunk
(artery) and the left ventricle are the chief constituents of this part
of the mediastinal shadow.

6 . The lungs. These show the relatively dense root shadows re-
sulting from the superimposition of the shadows of the pulmonary
and bronchial vessels, the bronchi and lymph nodes. The lung fields
are relatively transradiant because of the air they contain and the
pulmonary vessels are seen as shadows, i.e. white markings, super-
imposed on them. When vessels are seen end-on they appear as small
round white shadows.

[iMi

\v

iiTTiftl

sternomastoid

fst thoracic
vertebra

Shadow of a
branch of the
left pulmonary
artery seen
end on

Left border
of mam
pulmonary

Right breast
shadow

Rt cupola of
diaphragm

Cosiophrenic I
angle

C

stomach

Fig. 1 1.9 Radiograph of the chest of a female subject. Posterior projection.

arbitrary and do not bear any particular relationship to the under-
lying lobes of the lung. Crossing the middle zone on the right is a
very thin white line caused by the horizontal fissure which separates
the upper from the middle lobe.

Pathological Considerations

Tuberculous infection occurritig in childhood often involves one
of the lungs and it frequently heals with calcification in the lung and
hilar lymph nodes, the so-called primary complex. In adult life
tuberculous lung lesions occur most frequently in the apices of the

PATHOLOGICAL CONSIDERATIONS I57

upper lobes. Acute inflammatory conditions such as pneumonia
apd lung abscesses cause consolidation and thus render the affected
part of the lung more opaque to X-rays. If a bronchus becomes
blocked the air beyond it will be absorbed and the part of the lung
to which the bronchus is running will collapse.

A pleural effusion is a collection of fluid in the pleural space and
if the fluid is purulent it is called an empyema, A haemothorax is a
collection of blood in the pleura and it is usually the result of a chest
injury. Air in the pleural cavity is called a pneumothorax and if fluid
is also present the condition is known as a hydropneumothorax. In the
latter condition a radiograph taken with a horizontal beam will
show the upper surface of the fluid as a ‘fluid level’.

Obstructive emphysema is a condition in which one or both lungs are
more than normally distended with air because of a hindrance to the
free flow of air in a bronchus. BronchiectaHs is characterized by
dilatation of the bronchi which may contain pus; the condition may
be detected in plain radiographs of the chest but usually the instilla-
tion of opaque material into the bronchial tree (bronchography)
will be required.

Many pulmonary diseases cause the patient to cough up blood
and this symptom is callod haemoptysis.

12

The Lymphatic and Reticuloendothelial
Systems

THE LYMPHATIC SYSTEM

The cells of the various structures and tissues of the body are not
all in close contact with the blood capillaries, so they cannot directly
receive nutriment from the blood or pass their excreta into it. An
intermediary is required and this is provided bythe lymph. Lymph
is derived from the blood plasma; it permeates the tissues where
it is known as tissue fluid occupying the intercellular spaces and so
comes into intimate contact with the individual cells, linking them
with the neighbouring blood capillaries. The lymph is ultimately
returned to the blood stream as lymph travelling in vessels known
as lymphatics.

The lymphatics start as vessels of capillary size in the tissue spaces
and these converge on larger vessels which, as a rule, run with the
veins; like the veins they have valves to prevent the flow of their
contents in the wrong direction. Most of the lymphatics of the body
are too small to be visible to the naked eye. The two main lym-
phatic ducts, the thoracic and the right lymph ducts are, however,
large enough to be seen and all the lymphatics of the body ulti-
mately drain into either of them.

The thoracic duct receives lymph from both lower limbs and the
abdominal organs and just before its termination it receives lymph
from the left side of the remainder of the body. This duct starts in a
sac-like structure, the cisterna chyli which measures about 4 inches
(10 centimetres) long and \ inch (i centimetre) wide which lies in
front of the first lumbar vertebra where it reecives lymph from the
lower limbs and abdominal organs. The thoracic duct runs upwards
through the thorax between the vertebral column and the oeso-
phagus to enter the root of the neck, where it turns to the left and
joins the left subclavian vein at its junction with the left internal
jugular vein. Before its termination the thoracic duct receives

158

THE LYMPHATIC SYSTEM

159

lymphatics from the left side of the thorax, the left side of the head
and neck and the left upper limb.

Lymph from the right upper limb, the right side of the thorax and
the right side of the head and neck joins the right lymph duct which is
only about inches (about 4 centimetres) in length and flows into
the right subclavian vein.

Most of the products of fat digestion in the alimentary tract are
absorbed into the lacteals, as the lymphatics of the small intestine are
called, 'riiese run in the mesentery and end in the cisterna chyli.
After a fatty meal the lymph from the intestine has a milky appear-
ance and is called chyle.

The Lymph Nodes

At intervals along the course of lymphatics groups of lymph nodes

Cervical nodes

R. internal
jugular vein

R subclavian
vein

R lymph _
duct

Paratracheal

nodes

Tracheobronchial

nodes

Portal fissure
nodes

Cisterna chyli

Inguinal nodes

Trachea
Thoracic duct

Aorta

.Stomach draining to
coeliac nodes

Small int. draining
to sup. mes. nodes

Large int. draining
to inf. mes. nodes
Para-aortic nodes
Common iliac nodes

Internal iliac nodes
External iliac nodes

Ar€M ol body drained by |
R. lymphatic duct shaded
black, all the unshaded
area drains into thoracic
duct

Fig. 1 2. 1 Diagram illustrating the thoracic duct and the positions of the
main groups of lymphatic nodes.

i6o

THE LYMPHATIC SYSTEM

are found. These structures are also (incorrectly) called lymph
glands and consist of fibrous tissue and collections of cells similar to
the lymphocytes of the blood. They act as filters and extract such
things as bacteria and malignant cells from the lymph. The vessels
which bring lymph to the node enter the convex surface, and are
called the afferent lymphatics and the one which leaves the concave
surface or hilum is the efferent lymphatic. In addition to its action as
a filter the node has a completely separate function for within it are
the germ centres where the lymphocytes of the blood are manufactured
and these cells are then carried to the blood stream by the lymph.

In many parts of the body the lymph vessels and nodes are
arranged into superficial and deep sets. The superficial are found in
the superficial fascia (the fatty layer beneath the skin) and the deep
are found in the neighbourhood of the deep blood vessels. There arc
also collections of lymphoid tissue in the nasopharynx, the oro-
pharynx and the small intestine, these are called the adenoids, the
tonsils and the Peyer’s patches respectively. Sirfiilar tissue is also
present in the spleen.

Medulla

Efferent lymph
vessel

Capsule

Fig. ia.2 A lymph node on section (diagrammatic). Note the valves in
the lymph vessels.

The Lymph Nodes of the Head and Neck

These are divided into superficial and deep groups. The super-
ficial may be regarded as being distributed in a ring round the base
of the head and are subdivided into the submental which lie beneath

THE LYMPHATIC SYSTEM

l6l

the chin, the submandibular which are between the lower border of
th^ mandible and the submandibular salivary gland, the auricular
which are in front of and behind the ear and the occipital which lie
posteriorly. They drain into the deep cervical lymph nodes.

The deep nodes run with the internal jugular veins and are
divided into upper {superior) and lower {inferior) sets on each side. The
upper group receives lymph from the tonsils, tongue, mouth and
superficial tissues and drains into the lower group.

The efferent lymphatics from the inferior group drain on the right
side into the right lymph duct and on the left side into the thoracic
duct.

The Axillary Lymph Nodes (See Fig. 12.5)

These drain the upper limb and the upper and outer part of the
breast. I'hey are arranged in a lateral group along the axillary vein,
a posterior group along the posterior axillary margin, an anterior
(or pectoral) group along the anterior axillary fold and an apical
group at the apex of the axilla.

Efferent vessels go from these nodes into the right lymph duct on
the right side and into the thoracic duct on the left side.

The Thoracic Lymph Nodes

These arc divided into those of the chest wall, namely the internal
mammary (anterior mediastinal), the intercostal and the diaphragmatic

3

Fig. 12.3 The lymph nodes of the middle mediastinum, i. Para-
tracheal. 2. Tracheobronchial. 3. Bronchopulmonary.

i 62 the lymphatic system

and those which drain the thoracic contents, the middle and posterior
mediastinal nodes.

The middle mediastinal (See Fig. 12.3) nodes are situated along the
trachea and main bronchi and receive lymph from the lungs. Those
along the trachea are the paratracheal and those at the bifuscation of
the trachea are called the tracheobronchial nodes. The bronchopulmonary
nodes arc found at the roots of the lungs.

The posterior mediastinal nodes are situated along the descending
aorta and oesophagus and receive lymph from the oesophagus ; they
communicate with the middle mediastinal group.

Lymph from the mediastinal nodes on the right side drains into
the right lymph duct and on the left side into the thoracic duct.

The Abdominal Lymph Nodes

These nodes are divided into the visceral and parietal groups.

The visceral nodes arc situated along the branches of the coeliac axis
and the superior and inferior mesenteric arteries close to the organs
they drain, namely, the stomach, the liver, the gall bladcr, the
spleen, the pancreas and the intestines. Thus the gastric nodes are
found along the greater and lesser curvatures of the stomach and the
mesenteric nodes lie between the layers of the mesentery. Efferent
lymphatics pass from these visceral nodes to the aortic nodes of the
parietal group.

The parietal nodes are distributed around the abdominal aorta and
along the external, internal and common iliac vessels. In addition to
receiving lymph from the visceral nodes already mentioned these
nodes also receive lymph from the lower limbs, the pelvic viscera
and the organs of the posterior abdominal wall. Efferent vessels (the
right and left lumbar trunks and the intestinal trunk) pass to the cisterna
chyli.

The Inguinal Lymph Nodes

These are situated in the groin immediately below the inguinal
ligament. They receive lymph from the lower limb, buttock and
external genital organs; efferent lymphatics pass to the iliac group
of parietal abdominal nodes.

THE ADENOIDS

The lymphoid tissue on the posterior wall of the nasopharynx
(p. 145) is called the adenoids if it is enlarged.

THE LYMPHATIC SYSTEM

163

THE TONSILS

•There are two oval masses of lymphoid tissue lying in the lateral
walls of the oropharynx between the pillars of the fauces called the
tonsils. They merge with lymphoid tissue on the posterior part of
the tongue.

^EtER’S PATCHES

The collections of lymphoid tissue in the lower part of the ileum
are known as Peyer’s patches.

Lymph Drainage of Certain Structures*

1. The tonsil. Lymph drains into the upper deep cervical nodes of
the same side.

2. The touifue (see Fig. 12.4). Lymph from the dorsum of the
anlcrioi' part of the tongue and the entire posterior portion of the
organ passes directly into the upper and lower deep cervical nodes
oiboth sides. Lymph from the tip of the tongue passes first to the sub-
mental nodes and from each side of the tongue it goes first to the
submandibular group of the same side; from these sets of superficial
nodes the lymph passes to the deej) cervical nodes.

Internal

jugular

vein

Fig. 12.4 Lymph drainage of the longue (diagraminalic). i. Sub-
mental nodes. 2. Submaxillary nodes. 3. Upper deep cervical nodes.
4. T.ower deep cervical nodes.

I'he fact that much of the tongue drains to the lymph nodes of
both sides is of great clinical importance since malignant disease of
the tongue is likely to require treatment of the lymph nodes on each

* To avoid repetition of matter which has already been presented in this chapter
the lymph drainage is only described as far as the regional lymph nodes.

THE LYMPHATIC SYSTEM

164

side of the neck unless the lesion is a very early one and is limited to
the lateral border of the anterior two- thirds of the organ.

3. The thyroid gland. The upper part of the gland drains into the
upper deep cervical nodes and the lower part of the gland drains
into the paratracheal nodes of the middle mediastinum, m

4. The breast. (See Fig. 12.5) A network of lymphatics is present
in the breast substance and beneath the areola (the pigmented area
in the centre of which is the nipple). The lymphatics which leave
the breast communicate with those in the deep fascia overlying the
pectoralis major muscle. From the upper and outer parts of the
breast efferent lymphatics pass into the anterior (pectoral) and
apical groups of axillary nodes. Efferent lymphatics from the medial
part of the breast drain into the internal mammary (anterior
mediastinal) nodes and also some lymphatics pass across the midlinc
to communicate with those of the inner part of the opposite breast.
From the lower part of the breast lymphatics pass to the anterior
abdominal wall.

Fig. 12.5 Lymph drainage of the breast (diagrammatic). 1. Apical
axillary nodes. 2. Lateral axillary nodes. 3. Pectoral nodes. 4. To
abdominal wall. 5. To anterior mediastinal nodes along internal
mammary artery and communications with opposite breast. Note no
attempt has been made to indicate! the structures overlying the various
lymph nodes.

Cancer of the breast may be treated by a radical operation in
which an effort is made to remove all the tissue which may be

THE LYMPHATIC SYSTEM

165

affected and diseased; in this the surgeon removes the breast, the
de,ep fascia and pectoralis major, and all the axillary lymph nodes.

5. The lungs. The pulmonary lymphatic vessels consist of a super-
ficial network beneath the visceral pleura and a deep network which
follows the bronchi and pulmonary vessels. Both transmit lymph to
the nodes of the middle mediastinum, i.e. the bronchopulmonary and
tracheobronchial nodes (see Fig. 12.3). Communications with the
posterior mediastinal and paratracheal nodes also occur.

6. The small intestine. I'he lacteals (see p. 159) conduct the lymph
from the small intestine to the pre-aortic nodes at the origin of the
superior mesenteric artery.

7. The colon. Lymph passes from the colon to nodes along the
mesenteric vessels and thence to the pre-aortic nodes at the origins
of the superior and inferior mesenteric arteries.

8. The rectum and anal canal. Some lymphatics pass to the nodes
situated along the internal iliac (hypogastric) and common iliac
arteries and others from the highest part of the rectum run with the
superior haemorrhoidal vessels to drain into nodes in the sigmoid
mesocolon from which efferent vessels drain into the inferior
mesenteric group of pre-aortic nodes.

9. The bladder. Lymphatics pass from the bladder to the external,
internal and common iliac lymph nodes. From these groups of nodes
efferent lymph vessels pass to the lateral aortic (para-aortic) lymph
nodes.

10. The uterus. Lymphatics from the body of the uterus pass
laterally in the broad ligament and run with the ovarian vessels to
the lateral (para-) aortic and pre-aortic lymph nodes. From the
cervix lymphatics pass to the external and internal iliac lymph nodes
and to the common iliac nodes posteriorly.

1 1 . The vagina. Lymphatics pass from the vagina to the external
and internal iliac and sacral nodes. Below the hymen lymphatics
pass, with those of the vulva, to the inguinal nodes in the groin.

12. The ovary and testis. Lymph from these organs passes to the
abdominal aortic nodes.

Pathological Considerations

Bacteria may be arrested in lymph nodes and produce enlarge-
ment of them. This may subside, but if the node is destroyed an
abscess will form. Tuberculosis of lymph nodes often heals with the
deposition of calcium which renders them visible in a radiograph.
Malignant cells may be arrested in lymph nodes and they may grow
in the node and produce a secondary growth or metastasis.

l66 THE RETICULO-ENDOTHEM AL SYSTEM

Superficial lymphatics may become inflamed and they may be
seen as red streaks or bands running from a wound to the regional
nodes; the latter are likely to be tender and swollen.

Primary tumours of lymph nodes are usually growths of the
reticulo-endothelial elements which they contain. »

THE RETICULO-ENDOTHELIAL SYSTEM

This term is applied to collections of connective tissue-type cells
which are found in the spleen, liver, bone marrow, lymph nodes and
in the blood itself where they are known as the large mononuclear
cells. Most of them are capable of detaching themselves from the
tissues which in their resting state they help to form. They arc all
highly phagocytic and form part of the defences of the body against
infection.

Other functions of this system arc the removal of worn out red
blood cells by the spleen, the conversion of haemoglobin into bile
pigments by the liver and the storage of cholesterol.

THE SPLEEN

The spleen is situated in the left hypochondrium between the
fundus of the stomach and the diaphragm. It is about i inch (2.5
centimetres) thick, 3 inches (7.5 centimetres) wide and 5 inches
(12.5 centimetres) long. It consists of lymphatic tissue, blood spaces
and splenic pulp which contains much reticulo-endothelial tissue.

The spleen is in contact with the diaphragm on its convex surface
which faces backwards, upwards and laterally. Its medial surface is
in contact with the kidney posteriorly, the splenic flexure of the
colon inferiorly, the stomach anteriorly and in the middle of the
medial surface near the hilum, where the vessels enter and leave
the organ, it is in contact with the tail of the pancreas.

^^nctions of the Spleen

This organ is not essential to life; it is not infrequently removed
after rupture resulting from crush injuries and no ill cflTects neces-
sarily follow.

I. In virtue of the reticulo-endothelial tissue which it contains
one function of the spleen is to destroy Worn-out red blood cells.
From the destroyed cells the iron liberated is stored partly in the

THE RETICULO-ENDOTHELIAL SYSTEM 167

spleen and partly in the liver and in the latter organ the pigment of
the haemoglobin is converted into bile pigment.

2. The lymphatic tissue is concerned with the manufacture of
lymphocytes.

3. In embyronic life the spleen also produces red blood cells.

4. In view of the enlargement of the spleen which occurs in
typhoid fever, malaria etc. it is assumed that it makes antibodies.

5. The spleen is a spongy organ and can store blood. When a

sudden demand for blood is made it contracts and drives much of
the blood it contains into the circulation.

BONE MARROW

The bone marrow is found in the spaces between the trabeculae of
the bones. It is met with in two forms, the yellow and the red.

The red marrow is very vascular and is the site of manufacture of
the blood corpuscles. It is widespread in the newly born child, but
during childhood it is gradually replaced by yellow marrow which is
largely composed of fat. By the age of 20 the red marrow exists
principally in the vertebrae and in the flat bones such as the ribs,
skull, sternum, scapulae and pelvis.

There are parent endothelial cells in the red marrow from which
the primitive red blood cell (erythroblast), the primitive platelet
(megakaryoblast) and the primitive white blood cell (myeloblast)
are formed. In addition some lymphocytes are manufactured in the
bone marrow and the primitive lymphocyte (lymphoblast) also
develops from the parent cell in the bone marrow.

l68 THE RETIGULO-ENDOTHELIAL SYSTEM

Pathological Considerations

The reticulo-endothelial system is liable to neoplastic changes and
the tumours formed tend to be of widespread distribution. Innocent
tumours are very rare but malignant ones such as Hodgkin’s disease
and lymphosarcoma are not very uncommon. •

The reticulo-endothelial cells of the bone marrow may undergo
malignant transition causing diseases such as leukaemia and
multiple myelomatosis.

13

The Alimentary System

I

THE ALIMENTARY CANAL

The alimentary canal consists of the mouth, the pharynx, the
oesophagus, the stomach, the small and large intestines and certain
accessory structures such as the salivary glands, the liver, the biliary
apparatus and the pancreas.

THE MOUTH AND TONGUE

The mouth extends from the lips and cheeks anteriorly to the
anterior pillars of the faucej. posteriorly. These pillars arc the folds
of mucous membrane which run from the soft palate to the tongue,
'riie mouth is divided into the mouth proper which contains the tongue
and the vestibule. The latter is a recess between the cheeks externally
and the teeth and alveolar processes internally. On each side the
ducts of the parotid salivary glands open into the vestibule at the
summit of a small papilla opposite the second upper molar tooth.
The mouth is lined by mucous membrane which is moistened by
mucus and saliva.

The roof of the mouth is formed by the hard palate in front and
the muscular soft palate behind ; from the posterior margin of the
latter the uvula hangs down in the midline.

The floor of the mouth is principally formed by the tongue but
anteriorly it is composed of muscles. Anterior to the root of the
tongue and on either side of the midline are two small papillae on ^
which are the orifices of the ducts of the submandibular salivary glands.
Close to the opening of each of these ducts are a number of small
orifices through which the sublingual salivary glands discharge their
secretions.

The tongue is a muscular organ attached to the hyoid, the styloid
process of the temporal bone and the mandible. It consists of an
anterior or oral part and a posterior or pharyngeal part; these have

M 169

THE ALIMENTARY SYSTEM

170

different origins and a different superficial nerve supply but both
are composed of muscle bundles running longitudinally, transversely
and vertically. On the upper surface a V-shaped furrow separates
the anterior from the posterior part. The mucous membrane of the

anterior part is modified for the special function of tasting food and
bears numerous elevations known as papillas which contain the end-
organs for the sensation of taste, the taste buds (p. 263). The pointed

THE ALIMENTARY SYSTEM

Right InnoxD—
I Date vein

‘ Thyroid gland
‘Tracliea

"Left ionom-
loatn vein

Bight lung-]

\ Lafl lung

-Pericardium

JDlaphragm

Falciform*

ligament

Ascending
colon ”

- Tranaveme

colon

.Greater
omentum
(partly cut
away)

Pig. 13.2 The thoracic aiul abdominal contents exposed by removal ol the anterior
wall of the trunk.

' HaidpalMU

' Soft palate

^Anterior pillar
fauces

_ Posterior pillar of
fauces

" Tonsil

. Posterior pharyngeal
wall

Fig. 13.3 The mouth.

THE ALIMENTARY SYSTEM

Frenulum

Sublingual papilla of
Wharton*5 Duct

Fig. 13.4 The floor of the mouth and
the inferior surface of the tongue.

L>«W;

True Vocal Cord

False Vocal Cord

■ Cushion of the
Epiglottis

• — Epiglottis

^Pharyngeal part
of Tongue

CircumvallotQ

Papilla

Fungiform

Papilla

i3'5 dorsum of the tongue and the opening of the larynx.

The mouth ANt) TONGUE 173

filiform and the flattened fungiform papillae are distributed over
the dorsum, sides and tip of the anterior part of the tongue. The
largest papillae, the circumvallate, of which there are about twelve,
lie just anterior to the V-shaped groove separating the anterior from
the posterior parts of the tongue.

The posterior part of the tongue contains lymphoid tissue known
as the lingual tonsil.

In addition to being the organ of taste the tongue is also of
importance in speech, mastication and swallowing.

The tongue is innervated by certain cranial nerves and receives a
profuse blood supply from the two lingual arteries each of which is a
branch of the external carotid artery of the same side. The lymphatic
drainage has already been considered on page 163.

THE TEETH

The teeth are set in sockets in the alveolar processes of the jaws.
There are two sets, the temporary or fnilk dentition which erupts during
the first two and a half years and the permanent dentition which
replaces the milk teeth between the sixth and twelfth years. The
last teeth of the permanen^set, the wisdom teeth, usually erupt in
early adult life although they sometimes remain unerupted.

The temporary dentition consists of four incisor (or cutting), two
canine (or tearing) and four molar (or grinding) teeth in each jaw.
There are thus twenty teeth in the complete set.

The permanent dentition consists of four incisor, two canine, four
premolar and six molar teeth in each jaw. There are thus thirty-two
teeth in the complete set. I’his dentition differs from the first in
having premolar and third molar or wisdom teeth.

Temporary dentition

molar prcmol. can. inc. inc. can. prcmol. molar
upper 2 o I 2 2 I o 2

r=r20

lower 2 o 1221 o 2

Permanent dentition

upper 3 2 1221 2 3

--32

lower 3 2 1221 2 3

The arrangement of the teeth in the permanent dentition can be
described by the dental formula in which the teeth of each half of the
jaw are numbered consecutively from the first incisor, which is called

THE ALIMENTARY SYSTEM

174

number i, to the third molar, which is called number 8. A full
dentition in the left upper jaw would be expressed thus:

I 12345678

and in a request for a radiograph of the upper right posterior
premolar tooth the tooth in question will be indicated thus :

5 I and for the left lower lateral incisor thus | 2 .

That part of the tooth which projects beyond the gum is called
the crown\ the root is embedded in the alveolus and is separated from
the crown by the neck. The root is enclosed in a substance called
cement which is bound to the socket by the periodontal membrane as the

periosteum of the alveolus is called. The cortical bone of the socket
is called the lamina dura and is usually easily identified in a radio-
graph. The crown is covered by a dense white substance called
enamel and the bulk of the tooth is made up of a modified form of
bone called dentine. Within the tooth is a cavity called the pulp
cavity which contains blood vessels and nerves.

The incisors and canine teeth have roots which consist of a single
fang but the premolars have two fings and are sometimes called the
bicuspid teeth; the molars have three fangs and are also called the
tricuspid teeth.

THE SALIVARY GLANDS

*75'

1 Canine

UPPER

LOWER

THE SALIVARY GLANDS

There are three pairs of salivary glands and they secrete the
digestive juice of the mouth, the saliva. They are named the parotid,
the submandibular and the sublingual and their secretions are
carried to the mouth by ducts.

Fig. 13.8 Diagram illustrating positions of the salivary glands
of the left side. Note the deep part of the submandibular gland
and the sublingual gland are less heavily shaded.

The parotid gland is the largest and it lies below the external
auditory meatus between the ascending ramus of the mandible and
the mastoid process. A superficial part of the gland extends round
the posterior border of the ramus and lies lateral to the angle of the

176

THE ALIMENTARY SYSTEM

Sphenoidal sinus

Sup. concha

Sella turica

Frontal sinus

Naso-pharynx

Basi-pccipital ^

Naso-pharyngoal

tonsil —

laryngotymp. tube

Mid-concha

Inf. concha

Odontoid procoss

Soft palate

Oral part of -
pharynx

Epiglottis —

Laryngeal

part of pharynx

Thyro-hyroid lig. — ]

\Genioglossus

* Symphysis
menti

Sinus of larynx -
Cricoid cartilage

\ Geniohyoid

\ Hyoid bone

Cricoid cartilage Thyroid cartilage

Fig. 13.9 Median section of the nasal cavity, mouth and pharynx.

THE SALIVARY GLANDS

177

mandible. The duct (Stenson’s) is 2 inches (5 centimetres) long and
runs forward from the superficial portion of the gland through the
c 4 ieek to enter the mouth at the apex of a small papilla opposite the
second upper molar tooth.

The submandibular gland lies on the deep surface of the posterior
part of the body of the mandible and its duct (Wharton’s) runs to

Fig. 13.10 (a) Radiograph of the neck in the lateral pro-
jection showing the soft tissues.

the floor of the mouth to end at the summit of a small papilla
beside the frenulum (see Fig. 13.4) of the tongue.

The sublingual gland is situated beneath the mucous membrane of
the anterior part of the floor of the mouth and discharges its secre-
tions directly into the mouth through several small ducts which open
in the vicinity of the orifice of the submandibular duct.

THE ALIMENTARY SYSTEM

is an alkaline fluid containing the enzyme ptyalin in addition
to mucin and water. The action of saliva is to moisten the food and
lubricate it during swallowing, and the particular function of
ptyalin is to convert starch, which is a carbohydrate occurring in
bread, potatoes and certain other vegetable foods, into glucose.
Ptyalin can only act on cooked starch, for uncooked staith grains
are protected by a cellulose covering. Food does not linger long
enough in the mouth for much starch to be digested but the process
continues in the stomach until the gastric acid has become mixed
with the swallowed food and has neutralized the alkalinity of the
saliva.

THE PHARYNX

The pharynx lies behind the nasal cavities, the mouth and the
larynx. It is a muscular and membranous tube in front of the upper
four cervical vertebrae extending from the base of the skull to the
cricoid cartilage where it becomes continuous wi^h the oesophagus.
It is divided into three portions, the nasopharynx, the oropharynx
and the laryngopharynx.

THE PHARYNX I 79

The nasopharynx is part of the respiratory tract and was described
on p. 145.

The oropharynx extends from the level of the soft palate to the
epiglottis below. It lies behind the mouth and is separated from it by
the anterior pillars of the fauces. On the lateral wall of this part of
the pharynx are the posterior pillars of the fauces, and between the
anterior and posterior pillars on each side are the pharyngeal tonsils.
These are the tonsils which are liable to infection and arc frequently
removed surgically.

The laryngopharynx extends from the upper border of the epiglottis
to the lower border of the cricoid cartilage; it connects the oro-
pharynx to the oesophagus and lies principally behind the laryngeal
cartilages, although it also extends on either side of the upper part
of the larynx where it constitutes the pyriform fossae (sing, fossa).

The Appearances seen in the Lateral Soft Tissue Radiograph
of the Neck (Figs. 13.10^ and b)

Part of the base of the skull, the mandible, the hyoid and the
cervical vertebrae are seen. In front of the spine is a shadow caused
by the prevertcbral soft tissues and the posterior wall of the pharynx.
The air-containing naso]:^harynx, oropharynx, hypopharynx and
trachea are shown as shadows of low density. The epiglottis projects
upwards from the larynx and is separated by the vallecula from the
tongue which casts a conspicuous shadow in the mouth. The cricoid
and thyroid cartilages may be sufficiently calcified to cast shadows
and sometimes calcification is also present in the tracheal rings. In
front of the trachea a soft tissue opacity produced by the pretracheal
muscles and the isthmus of the thyroid gland may also be seen

THE OESOPHAGUS

The oesophagus is a muscular tube about 10 inches (25 centi-
metres) long extending from the pharynx to the cardiac orifice of the
stomach. It consists of an outer fibrous coat, longitudinal and cir-
cular muscle coats and mucous membrane. It starts at the level of the
cricoid cartilage opposite the sixth cervical vertebra and has cervical,
thoracic and abdominal parts.

Relations of the cervical part of the oesophagus. I'his portion runs be-
tween the trachea which lies in front and the vertebral column be-
hind. The common carotid arteries and the posterior parts of the
lateral lobes of the thyroid gland are on either side.

THE ALlMENtARY SYSTEM

ido

Relations of the thoracic part of the oesophagus. The oesophagus runs
through the superior mediastinum, in front of the thoracic duct and
vertebral column and behind the trachea. It then passes into the
posterior mediastinum where it continues to lie in front of the
thoracic duct and vertebral column and just above the diaphragm,
which it pierces at the level of the tenth thoracic vertebra, it passes
in front of the descending thoracic aorta. The oesophagus runs
through the posterior mediastinum on the right of the descending

Oesophagus Trachae

R. bronchus

Thoracic

sympathetic

trunk

Greater

splanchnic

nerve

Aorta

L bronchus

Diaphragm

Stomach

Fig. 1 3. 1 1 The thoracic portions of the trachea, the oesophagus and the aorta.

aorta to which it is loosely attached; it lies behind the right pulmon-
ary artery and the left main bronchus and below these it is behind
the pericardium and left atrium. On the right side are the azygos
vein and the right pleura; on the left are the aortic arch, the de-
scending aorta and the left pleura.

Relations of the abdominal part of the oesophagus. This part is only | of
an inch (2 centimetres) long and it is related anteriorly to the liver.

Structure of the oesophagus. The oesophagus consists from without

tHE ABDOMINAL CAVITY l8l

inwards, of fibrous, longitudinal and circular muscular coats, a sub-
mucous layer and, innermost, the mucous membrane consisting of
stratified epithelium.

The Radiographic Appearances of the Oesophagus

In the right anterior oblique position the swallowing of barium
cream will demonstrate the oesophagus throughout its length. The
narrowest parts of the structure are seen to be at its commencement,
at the level of the bronchial impression, and at the lower end. The
impression on the anterior wall due to the aortic arch will be seen,
below this is the impression caused by the right pulmonary artery
and left main brochus, and still further down is the long smooth
impression caused by the pericardium and left atrium.

THE ABDOMEN

'I’he abdomen consists of the abdominal cavity proper and the
pelvic cavity. The first of these extends from the pelvic brim below
to the diaphragm above; it is bounded anteriorly and laterally by
the abdominal muscles, lower ribs and iliac bones and posteriorly by

the posterior abdominal muscles and lumbar vertebrae. It is lined
by peritoneum and contains the stomach, the small and large
intestines, the liver, the pancreas, the gall-bladder, the kidneys, the
spleen, the suprarenal glands and the great vessels of the abdomen.

The pelvic cavity is bounded by the hip bones and sacrum and
contains the lower part of the large intestine, the bladder and, in the
female, the genital organs.

the alimentary system

182

The surface markings of the abdomen are dealt with on page 268
et sqq.

THE ABDOMINAL REGIONS

Certain regions of the abdomen are named for descriplive pur-
poses. The boundaries of these regions consist of two lateral lines
drawn through the midpoint between the anterior superior iliac
spine and the symphysis pubis on each side; and two horizontal

Fig- * 3- *3 (®) Radiograph of structures seen in the posterior projection
of the abdomen without the use bf contrast media. {Note this subject
has six lumbar vertebrae. The more usual arrangement is illustrated in
Fig. 14.6.)

THE ABDOMEN

183

lines, one of which, the transpyloric planed is approximately midway
between the xiphisternal joint and the umbilicus, and the other, the
intertubercular plane, is drawn between the tubercles on the outer parts
of the iliac crests. These lines demarcate nine regions; the upper row
consists of the right and left hypochondriac with the epigastric separating
them, the next row consists of the two lumbar regions separated by
the umbilical and in the lowest row are the iliac regions with the
hypogastric between them. (The hypochondriac, epigastric and
hypogastric regions may also be called the hypochondrium, the
epigastrium and the hypogastrium respectively.)

Radiographic Appearances of the Abdomen without the
use of Contrast Media

The posterior projection in the supine position shows the dia-
phragm, the lower ribs and the intercostal spaces in the upper part

Fig. 13.13 (b) Line drawing of {a).

* Some authorities do not use the transpyloric plane for separating the two
upper rows but employ the subcostal plane which passes through the loth costal
cartilages. The former plane is of much greater practical value and there is no
need for the student to burden his memory with the subcostal plane.

184 the alimentary system

of the radiograph and the sacro-iliac joints, the pelvic bones and the
pelvic cavity in the lower part. Running down the middle of
the radiograph are the lower thoracic and lumbar vertebrae and the
sacrum; on either side the lateral borders of the psoas muscle cast
shadows which pass downwards and laterally from the twelfth
thoracic vertebra.

The uniform opacity in the upper abdomen is caused by the
liver. The shadow of the spleen may be seen in the left ninth and
tenth interspaces and the kidneys are usually clearly visible because
they are surrounded by a transradiant line produced by the peri-
renal fat (p. 210). Some gas may be seen in the stomach and intes-
tines and faecal material also may be seen in the large bowel. The
bladder, if it contains sufTicient urine, will cast a shadow in the
pelvis.

THE PERITONEUM

The peritoneum is a serous membrane like the pleura. It is thin
and slightly moist and it covers many abdominal organs either
partially or completely. It enables the organs which it covers to
move without friction and it holds some in position by forming
ligaments and mesenteries. A curtain-like fold of peritoneum, the
greater omenturrij has a protective function, for its free border may
become adherent to an inflamed or injured surface and thus it may
prevent contamination of the peritoneal cavity. The greater
omentum is often heavily laden with fat and constitutes one of the
fat stores of the body.

It is difficult to understand the relationship which exists between
the abdominal viscera and the peritoneum without a knowledge of
embryology. However, if the abdominal cavity is first imagined to
be empty and simply lined with peritoneum - the parietal peri-
toneum^ then the various organs must be pictured developing on the
posterior abdominal wall. Some of these will have peritoneum only on
their anterior surfaces and they are said to be retroperitoneal \ others
may bulge into the cavity pushing up the peritoneal covering on the
posterior abdominal wall so that they are covered on their fronts and
sides by it. Others will push their way so far into the cavity that they
drag the peritoneum off the posterior abdominal wall as a double
fold in which are their blood vessels, nerves and lymphatics. This is
what much of the bowel does so that it is intraperitoneal, being covered
by the visceral layer of peritoneum and suspended from the posterior
abdominal wall by a structure known as the mesentery. This arrange-

THE PERITONEUM

185

ment is greatly complicated by the enormous increase in length
vyhich the small intestine undergoes so that the mesentery by which
it is suspended is fan-shaped and measures about 5 inches ( 1 2 centi-
metres) long at its base on the posterior abdominal wall but about
20 feet (6 metres) in length at its attachment to the bowel.

Liver

CastrO’hepatic

omentum

Stomach

Transverse

colon

Greater

omentum

Small intestine

Lesser Sac
Pancreas

Duodenum

Transverse

meso-colon

Mesentery of
small intestine

Fig. 13.14 Diagram of a sagittal section of the abdomen to show the disposition of
the peritoneum.

The stomach and first part of the duodenum are suspended by the
lesser omentum and the greater omentum hangs down from the greater
curvature of the stomach.

In the pelvis the parietal peritoneum covers the front of the
rectum and passes forwards, in the male, to the posterior surface of
N

l86 THE ALIMENTARY SYSTEM

the bladder; in the female it covers the anterior and posterior walls
of the uterus also. Between the rectum and the 'Uterus is a recess
known as the recto-uterine pouch (or the Pouch of Douglas).

The peritoneal cavity in the male is a completely closed space but
in the female it communicates with the exterior through th« uterine
tubes (p. 224) which open into it.

^HE STOMACH

The stomach is the most distensible portion of the alimentary
tract and transmits food from the oesophagus to the duodenum. It
varies greatly in size, form and position in different people and in
the same individual at different times of the day. It is the most
distensible portion of the digestive tract, is J-shaped and lies in the
left hypochondriac, epigastric and umbilical regions.

The stomach consists of a dome-shaped upper part, the fundus^
which is usually filled by the ‘gas bubble’ in the erect position. The
cardiac orifice the upper opening into the stomach and the oesophagus
enters through it. The upper border is called the lesser curvature and
the lower border to which the greater omentum is attached is called
the greater curvature. About two-thirds of the way down the lesser
curvature is the angular notch and this divides the body of the stomach
from the pyloric portion^ which is subdivided into the pyloric antrum
and the pyloric canal. The pyloric sphincter, a thick ring of circular
muscle, surrounds the pyloric canal and controls the passage of
gastric contents into the duodenum.

Relations of the stomach. The left lobe of the liver and the abdominal

Fig- 13- *5 Diagram illustrating the parts of the stomach.

THE SMALL INTESTINE 187

wall are in front of the stomach, and the structures of the ‘stomach
bed’ which include the spleen,, the left suprarenal gland, the left
kidney and the pancreas lie behind it.

Structure of the stomach. The stomach consists of an outer peritoneal
coat, a muscular coat consisting of longitudinal, transverse and
oblique layers in this order from without inwards, a submucous coat
and a mucous membrane thrown into folds known as rugae.

SStie Functions of the Stomach

The stomach acts as a reservoir for food and it secretes hydro-
chloric acid and certain enzymes. The salivary enzyme ptyalin
continues to act until the acid has permeated the swallowed food.
The enzymes secreted by the stomach include (i) pepsin which in the
presence of acid turns proteins into peptones, and (2) rennin which
curdles milk; the protein of the curd is then digested by the pepsin
in the same way as other protein food.

The secretion of gastric juice results from psychic stimuli, such as
the sight and smell of food and direct stimuli, such as the presence of
food in the organ.

Another function of the stomach has already been mentioned
(p. 1 41) namely, the fofhiation of the ‘intrinsic factor’ which with
the ‘extrinsic factor’ in the food is elaborated Into the anti-anaemic
factor by the liver.

^TllE SMALL INTESTINE

The small intestine extends from the pylorus of the stomach to the
ileocaccal valve where it joins the large intestine. It is about 20 feet
(6 metres) long and is divided into the duodenum, the jejunum and ^
the ileum.

The duodenum. This part is about 10 inches (25 centimetres)
long and lies on the posterior abdominal wall ; for the most part it is
retroperitoneal. It is C-shaped, embracing the head of the pancreas
in its concavity and is divided into four parts. The first part is
horizontal, lying in front of the hepatic artery and common bile duct
and it has a short intraperitoneal portion known as the ‘cap’ which
is immediately beyond the pylorus. The second part descends in
front of the right kidney and inferior vena cava and at about the
middle of its medial wall is the duodenal papilla where the orifices
of the common bile duct and pancreatic duct are situated. The third
part crosses the midline, while the fourth part ascends to become
continuous with the jejunum at the duodenojejunal flexure.

THE ALIMENTARY SYSTEM

l88

“•the jejunum and ileum. These portions are intraperitoneal
and are suspended from the posterior abdominal wall by the
mesentery, in which run their blood vessels, lymphatics and nerves.
The jejunum starts at the duodenojejunal flexure and lies mainly
in the umbilical region; it is about 8 feet (2.5 metres) longhand the
ileum with which it is continuous is about twelve feet (3.7 metres) in
length.

R. supra
renal gland

R. and L
lepatic ducts
(cot)

Duodenum

Spleen

L supra-
renal gland

Pancreatic

duct

Duodeno-

jejunal

flexure

L kidney
(cut)

Head of
pancreas

Fig. 13. 16 Diagram showing the viscera which lie on the posterior abdominal wall.
The dotted outline indicates the position of the liver. The duodenum is cut open
to show the common opening of the bile and pancreatic ducts.

!K^tructure of the Small Intestine

The small intestine consists of an outer peritoneal coat, a
muscular coat made up of longimdinal and circular layers, a sub-
mucous and a mucous coat. The innermost layer of the mucous coat
is the mucous membrane which is thrown into permanent folds
known as the circular folds to increase the surface area for food
absorption; there are also crinkly corrugations caused by contrac-
tion of the muscularis mucosae which is a muscular layer in the deeper

THE SMALL INTESTINE

189

part of the mucous coat. In certain conditions of the small bowel
these latter contractions may be deficient and their absence can be
demonstrated radiographically.

The mucous membrane of the small bowel has a velvety appear-
ance produced by numerous microscopic projections called villi
which are richly supplied with blood vessels. Their presence results
in a very large surface area of the intestinal wall being brought into
contact with the contents of the bowel.

In the mucous coat of the lower ileum deep to the mucous mem-
brane there are characteristic collections of lymphoid tissue known
as Peyer's patches which are of some medical interest as they become
inflamed in typhoid fever.

Intestinal

gland

^Functions of the Small Intestine

The upper part of the small intestine is mainly digestive in func-
tion and the lower part is principally concerned with absorption.
Food in the process of digestion is called chyme and it enters the
duodenum from the stomach at frequent intervals after the taking
of a meal.

The contents of the duodenum are rendered /alkaline by the bile
and this alkalinity is necessary for the action of the three pancreatic
enzymes which enter the duodenum from the pancreas. These
enzymes are trypsin which digests protein, amylase, which digests
uncooked as well as cooked starch and lipase, which breaks fats up
into fatty acids and glycerine. The trypsin is a more potent proteii?

THE LARGE INTESTINE I9I

splitting enzyme than pepsin for it acts on peptones and turns them
into substances called polypeptides.

The digestion of starch, protein and fats is taken further in the
jejunum where enzymes are secreted by the intestinal wall in a
fluid called the succus entericus.

The digestive juices are powerful substances and the reader may
wonder why it is that they do not destroy the walls of the organs in
which they are produced. It is thought that, in addition to the
mucus which the walls of the alimentary canal produce, they also
secrete ‘anti-enzymes’ which counteract the effects of the enzymes
in their immediate vicinity. It is a well-known fact that the juices
will digest skin and muscle of the abdominal wall if they leak out
through, for example, a pancreatic fistula.

The absorption of the products of digestion occurs chiefly in the
small intestine although water, salts and glucose are absorbed from
the stomach and large intestine also. Glucose results principally
from the digestion of carbohydrates; polypeptides and amino-acids
result from protein digestion. These substances and water with
mineral salts in solution enter the capillaries of the villi and pass via
the mesenteric veins to the portal system (p. 138). Fatty acids and
glycerol resulting from the digestion of fat take a different route,
for they enter the lymphatics (the lacteals) of the villi giving the
lymph, which is now called chyle (p. 159), a milky appearance. The
chyle passes to the cisterna chyli whence it goes via the thoracic duct
to the left subclavian vein where it enters the blood stream and is
carried round the body. The products of fat digestion are deposited
in the fat stores of the body (the subcutaneous tissues, etc.) as
saturated fats. When the fat stores are required for the production of
energy desaturation ( the ^ removal of some hydrogen) must take^
place in the liver, to and from which they are carried by the blood
sticam.

THE LARGE INTESTINE

The large bowel extends from the ileocaecal junction to the anus;
it is about 5 feet (1.5 metres) long and consists^of the caecum and
vermiform appendix, the ascending, the transverse, the descending
and pelvic parts of the colon and the rectum and anal canal.

The caecum is a dilated pouch-like structure into which the ileum
opens through the slit-like ileocaecal valve. It is covered by peritoneum
and from it the vermiform appendix projects in a variety of positions.
The appendix is a worm-like structure, as its name indicates, about
4 inches (10 centimetres) in length, it ends blindly and is possessed of

192

THE ALIMENTARY SYSTEM

a small mesentery. It is lined by mucous membrane which is contin-
uous with that of the caecum and it contains lymphoid tissue in its
walls.

The ascending colon lies in the right lumbar region running
upwards from the caecum to the under surface of the liver where it
becomes the transverse colon at the hepatic flexure which lies in the
right hypochondrium. 'Fhe ascending colon lies behind the peri-
toneum being covered by peritoneum only on its anterior surface.

The transverse colon, which extends from the hepatic to the
splenic flexures^ has a mesentery called the transverse mesocolon and is
variable in position. It curves downwards as it crosses the abdomen
and then ascends to the splenic flexure which lies near the spleen in
the left hypochondium.

The descending colon runs downwards from the splenic flexure,
through the left lumbar region and left iliac fossa to join the pelvic
colon at the pelvic inlet. Like the ascending colon it is clothed by
peritoneum on its anterior surface and so is constant in position.

The pelvic (or sigmoid) colon is of variable length in different
individuals. Because it has a mesentery, called the pelvic mesocolon, it
is of variable position but it lies mainly in the cavity of the pelvis.

The rectum is continuous with the pelvic colon and is about
5 inches (12.5 centimetres) long. It lies in the pelvis in front of the
lower part of the sacrum and coccyx; it is intraperitoneal in its
upper part but extraperitoneal below. It is curved from side to side
as well as antero-posteriorly. The lower part of the rectum is ex-
panded and is called the ampullary portion. In front of the upper
part of the rectum coils of ileum lie in the lower part of the peritoneal
cavity; below this the rectum is related in the female to the uterus
and vagina and in the male to the bladder and prostate gland.

The anal canal is the terminal i inch (2.5 centimetres) of the
large intestine and is surrounded by the anal sphincters.

Structure of the large intestine. The large intestine may be considered
as consisting of three layers. The outermost consists of connective
tissue and peritoneum, which, in the ascending and descending
colon, is incomplete. Next comes the muscular coat which differs
from that of the rest of the intestine in that the longitudinal muscle
is not spread evenly round the circumference of the bowel but is
collected into three bands, the taeniae, which run from the caecum to
the upper part of the rectum. These bands are not as long as the rest
of the bowel wall, so they gather it up into sacculations known as
haustrations.

The innermost layer is composed of the submucosa of connective

THE LARGE INTESTINE

193

tissue, nerves, vessels and lymphatics and the mucous membrane
of columnar epithelium containing many cells which secrete
mucus.

Functions of the Large Intestine

This part of the alimentary canal is chiefly concerned with the
preparation, storage and evacuation of the indigestible and unab-
sorbable food residues known as faeces. This is accomplished partly

Bladder Prostate Vesicula seminalis

Symphysis

pubis

Membranous

urethra

Corpus

spongiosum

Corpus

cavernosum

Gians penis

Fossa

terminalis

Rectum

Ext

sphincter
of anal
canal

Anal canal

Testis Bulb of penis

*3- *9 Sagittal section of the male pelvis and external genital organs.

by reducing the bulk of the intestinal contents by the absorption of
water and the decomposition of cellulose by the bacteria which are
normal residents in the colon. Certain substances may be excreted
by the wall of the large intestine into the faeces, for example, the
salts of heavy metals such as bismuth and iron. The intestinal wall
also secretes mucus which lubricates and protects the mucous
membrane.

194

THE ALIMENTARY SYSTEM

THE RADIOGRAPHIC APPEARANCES OF THE
STOMACH AND INTESTINES

Radiographic Appearances of the Stomach

If a little barium emulsion is massaged over the mucous mem-
brane of the fasting stomach during a barium meal examination the
rugal folds will be seen. When the stomach is partly filled with the

Air in fundus
of stomach

Body of
stomach

Duodeno-

jejunal

junction

Duodenal

cap

Pylorus

Pyloric

antrum

Third part
of

duodenum

Fig. i3.ao (a) Normal stomach and duodenum immediately after ingest-
ing a barium meal.

emulsion and the subject is in the erect position the gas bubble in the
fundus will show above the fluid level at the top of the barium
column. The various parts of the stomach such as the greater and
lesser curvatures and the body and pyloric portions will be recog-
nized. Peristaltic waves (p. 197) will be sqen at fluoroscopy either
churning the contents or driving them through the pylorus.

195

RADIOGRAPHY OF SMALL INTESTINE

Radiographic Appearances of the Small Intestine

The duodenal cap is seen as a conical structure with its base
towards the pylorus. Since this part is intraperitoneal it is mobile and

Fig. 13.20 (b) Radiograph following ingestion of a small quantity of barium
showing the mucosal pattern of the duodenum and jejunum.

differs in its situation according to whether the patient is erect or
recumbent. Barium will pass rapidly through the remaining portions
of the duodenum under the influence of peristalsis and the mucosal
pattern is seen to be typical of that of the small intestine, it is

THE ALIMENTARY SYSTEM

196

produced by a combination of the circular folds and the corrugations
caused by contraction of the muscularis mucosae.

Radiographic Appearances of the Large Intestine

The colon may be demonstrated by the administration of 2 to 3
pints (2 litres) of barium sulphate emulsion per rectum. The entire

Fig. 13.20 (c) The large intestine demonstrated by a barium
enema. The terminal ileum is also shown.

large bowel may be seen in the posterior (A.P.) projection (see Fig.
i3.2o((:)) but oblique views of the sigmoid colon, hepatic and splenic
flexures and lateral projections of the rectum may be required. The
course of the large bowel can be studied ; its calibre is widest at the
caecum and rectum and narrowest at the vermiform appendix. The
characteristic haustral pattern is seen when the bowel is filled and

MOVEMENTS OF ALIMENTARY TRACT I97

after evacuation the length and calibre are diminished but the
mucosal pattern is demonstrated.

THE MOVEMENTS OF THE ALIMENTART TRACT

Deglutition (swallowing)

The act of swallowing is performed after food has been chewed
and compressed between the hard palate and the tongue to make a
bolus. This is passed into the pharynx where the soft palate is drawn
towards the posterior wall to prevent the bolus from entering the
nasopharynx. As this occurs the larynx is raised and the epiglottis is

Wave of
contraction

I

Wave of
relaxation

3

Fig. 13.2 1 Diagram illustrating a peristaltic wave
' passing along a short segment of a hollow organ
such as the bowel or ureter. The bolus of food
(in the bowel) is propelled in the direction in-
dicated by the arrows by a wave of contraction
preceded by a wave of relaxation.

deflected to cover the glottis and so prevent the entry of swallowed
material into the larynx. When the bolus enters the oesophagus the
act of swallowing becomes involuntary and peristaltic waves, aided
in the erect position by gravity, carry it down to the stomach.

Peristalsis

This term is used to describe the method by which involuntary
muscle propels material along hollow tubes; it consists of a relaxa-
tion occurring ahead of the material and a contraction following
behind.

Movements of the Stomach

These may be studied during barium meal examinations. The

igB THE ALIMENTARY SYSTEM

Tasting stomach will be found to be almost empty with its muscula-
ture contracted. As it is distended with the opaque material^muscular
contractions will be observed; initially these do not result in the
expulsion of stomach contents but are churning movements which
mix the food with the gastric juice. When the pylorus relaxes the
stomach will begin to empty and the time taken for this to occur
depends on many factors, the most important of which is the nature
of the food. Fatty foods and proteins are retained longer than
carbohydrates and a heavy rich meal may. stay in the stomach for
5 or 6 hours.

Movements of the Small Intestine

Three movements occur in the small intestine, segmentation,
pendulum movements and peristalsis. The intestinal contents
are churned up by a combination of segmentation and pendulum
movements: the former consists of contractions of the circular
muscle dividing the lumen into short segments, and the latter are
to-and-fro movements. Peristalsis starts in the lower part of the
duodenum and by frequent and rapid waves the chyme is propelled
into the distal part of the ileum where the bowel is much less active.
The entry of food or fluid into the stomach stimulates peristaltic
activity in the lower part of the ileum by the gastro-ileal reflex and
this results in the passage of the ileal contents into the caecum.

Movements of the Large Intestine

The large intestine does not exhibit continuous activity in the
way that the small bowel does, but peristaltic movements occur at
intervals especially after taking food as a result of what is called the
gastrocolic reflex. The contents of the large intestine are called
faeces and these ^are mainly stored in the descending and sigmoid
parts of the colon. It is probable that the rectum is usually empty
and it is the arrival of faeces in the rectum which gives rise to a
desire to defaecate.

Defaecation

The expulsion of faeces requires the relaxation of the anal
sphincter, the contraction of the rectum and certain accessory
muscles in the pelvis, and the assistance of a general increase in
abdominal pressure brought about by contraction of the diaphragm
and holding the breath.

THE LIVER

199

THE LIVER*

The liver is a large organ weighing over 3 lb. (1.5 kilogrammes).
It is irregular in shape but can be likened to a wedge with its base to
the right and its apex to the left. It lies principally in the right
hypochondrium but stretches across the epigastrium to reach the
left hypochondriac region. It is divided into two main lobes, a large
right lobe and a smaller left (see Fig. 13.2). The surface anatomy of
the liver is described on p. 270.

Intralobular

vein

Interlobular

vein

Duct

Arteries

Fig. 13.22 Minute structure of the liver.

Relations of the Liver

The upper surface is related to the under surface of the diaphragm ;
the anterior surface is related to the under surface of the diaphragm
and the adjoining part of the anterior abdominal wall. The posterior
surface of the liver is related to the diaphragm, the inferior vena cava,
the abdominal aorta and the oesophagus. The hepatic veins leave
the posterior surface to enter the adjacent inferior vena cava. The
inferior surface slopes upwards and backwards from the anterior
margin and is related, on the right, to the gall-bladder, the hepatic
flexure of the colon, the right suprarenal gland and right kidney and,
on the left, to the fundus of the stomach.

* Before studying the liver the student is advised to revise the portal venous
system (page 138).

200

THE ALIMENTARY SYSTEM

. The portal fissure (or the porta hepatis) is an opening on the under
surface through which the right and left hepatic ducts, the portal
vein and the hepatic artery pass.

The peritoneum covers most of the organ but is lacking over its
upper surface (the bare area of the liver) where it is refleoted to be-
come continuous with that on the under surface of the diaphragm.

Structure of the Liver

The liver is spongy in consistency and is enclosed within a thin
fibrous capsule. It is made up of many lobules between which are
tributaries of the bile ducts and the interlobular (inter = between)
branches of the hepatic artery and portal vein. In the centre of each
lobule is the intralobular (intra = within) vein, a tributary of the
hepatic veins.

The structure of the liver can be related to its functions for the
cells of the lobules are arranged in columns between which are blood
spaces known as the sinusoids and both portal venous blood (contain-
ing the products of digestion) and arterial blood mix in them. The
blood percolates through the lobule to reach the intralobular vein
whilst the bile which is made by the cells of which the lobule is com-
posed flows in the opposite direction to reach the interlobular tri-
butaries of the hepatic bile ducts.

It will be appreciated that the liver has a dual supply of blood -
oxygenated blood from the hepatic artery which arises from the
coeliac axis, a branch of the aorta, and portal venous blood from the
portal vein. The blood leaves the liver by flowing from the intra-
lobular veins into the hepatic veins which drain directly into the
inferior vena cava which is in contact with the posterior surface of
the liver.

Functions of the Liver

The liver may be compared with a chemical laboratory where
many complicated processes are occurring simultaneously. Some of
these functions are concerned with the conversion of absorbed food-
stuffs into substances required by the body for metabolism, some
are concerned with the storage and manufacture of material and
some with the detoxication of poisons and the excretion of various
substances. A few of these functions will be briefly dealt with.

The formation of bile. This is a continuous process between
one and two pints of bile being formed by the liver cells daily. It is
excreted into the tributaries of the hepatic ducts and passed to the

THE BILIARY APPARATUS

201

gall-bladder and duodenum. Bile contains pigments derived from
.haemoglobin and substances known as bile salts.

The formation of urea. The end-products of protein metabolism
result in the formation of nitrogen residues which are converted into
urea by the liver and excreted by the kidney.

Storage. Vitamins A and D, iron, the anti-anaemic factor
(pp. 14 1, 187) and glycogen (derived from glucose) arc amongst the
substances stored by the liver.

The production of heat. I'he chemical processes result in many
cases in the production of heat which plays an important part in the
maintenance of body temperature.

THE BILIARY APPARATUS

The biliary apparatus consists of the ducts through which the bile
is transported and the gall-bladder which concentrates it.

The bile ducts start as the interlobular bile capillaries in the liver,
which unite with vessels of increasing size and converge on the porta
hepatis to form the common hepatic duct. One and a half inches (3
centimetres) below this j|ie common hepatic duct unites with the

Liver

Left hepetic
duct

Common hepatic
duct

Common bite
duct

Pancreatic duct
Pancreas

Fig. 13.23 Diagram illustrating the biliaiy apparatus.

cystic duct from the gall-bladder to form the common bile duct. This duct
passes behind the first part of the duodenum and the head of the
pancreas closely related to the hepatic artery and the portal vein. It
then turns laterally to enter the duodenum at the summit of the
duodenal papilla; the pancreatic duct may open into its lower end
or both ducts may open separately on the dudoenal papilla.

The gall-bladder is a pear-shaped organ measuring 3 to 4 inches
(7 to 10 centimetres) in length and having a capacity of about one

o

202

THE ALIMENTARY SYSTEM

ounce (30 to 50 cubic centimetres). It is attached to the under side
of the liver and its blind end, the fundus, extends below the lower
margin of the liver in contact with the inner aspect of the anterior
abdominal wall at the level of the tip of the ninth costal cartilage
when the patient is supine. The cystic duct leaves the nock of the
gall-bladder. The duct is about i J inches (3.5 centimetres) long and
joins the common bile duct about 2^ inches (7 centimetres) above
its lower end.

dsopf^agus
Cardiac Onfice

Fundus

Gall Bladder

Pylorus

Common
Bile Duct

Duodenum

Ampulla
of Vater

Greater

Curvature

Spleen

Splenic Artery

Fig. 13.24 The stomach, pancreas and bile ducts, etc.

Structure of the biliary tract. The gall-bladder consists of an outer
peritoneal coat, a fibromuscular coat and, innermost, a mucous
membrane of columnar epithelium.

The bile ducts lack a peritoneal coat. They have a fibromuscular
coat and mucous membrane. The mucous membrane of the cystic
duct possesses a spiral fold, called the spiral valve, which is some-
times visible at cholecystography.

Function of the biliary tract. The function of the gall-bladder is to
concentrate and store bile and, under the stimulus of fatty food, to
contract and expel it into the duodenum. The function of the bile
ducts is to convey bile from the liver into and out of the gall-bladder
and to the duodenum. Thus bile passes in both directions through
the cystic duct. It will pass from the common hepatic duct into the
gall-bladder to be concentrate^ and when the gall-bladder con-
tracts it will be expelled back along the cystic duct and the common
bile duct will conduct it to the duodenun^.

THE BILIARY APPARATUS

203

Functions of Bile

Bile is an aqueous solution of bile salts and pigments and is
alkaline in reaction. The salts are necessary for the action of all the
pancreatic enzymes, they are important in the absorption of fatty
acids and glycerol, both of which are derived from fats, and they
exert an aperient action on the large intestine. No known function
is performed by the pigments which are responsible for the colour
of the faeces.

Radiographic Appearances of the Biliary System

Various iodine containing preparations may be given orally or
by injection to demonstrate the biliary system. When it is taken by

Common
hepatic duct

Cystic duct

Galt

bladder

Fundus of
gall bladder

Common
bile duct

Fig. 13.25 The gall-bladder and bile ducts outlined by telepaque. The
radiograph was taken after a fatly meal had caused the gall-bladder to

contract.

204 THE ALIMENTARY SYSTEM

mouth the opaque medium is absorbed from the small intestine and
carried to the liver, which excretes it into the bile. The opaque
medium will be concentrated with the bile in the gall-bladder and
when concentration is sufficient this structure will be visualized. If a
fatty meal is then given the gall-bladder will contract and the
cystic and common bile ducts will be rendered visible as the opaque
medium travels to the duodenum.

As with other intra-abdominal structures the position of the gall-
bladder depends on bodily type, phase of respiration, the state of
fullness of other organs and whether the subject is erect or recum-
bent. The organ is, however, usually described as lying in the angle
between the twelfth rib on the right and the upper lumbar vertebrae
but owing to the variations in its position the radiograph usually
includes the lower two ribs on the right, the lumbar spine and the
right iliac crest.

THE PANCREAS

The pancreas lies on the posterior abdominal wall at the level of
the first lumbar vertebra. It is retroperitoneal, about 6 inches (15
centimetres) long and consists of a head^ neck, body, and tail. The head
is enclosed on three sides by the duodenal loop and behind it are the
portal vein and the common bile duct. The body crosses the inferior
vena cava, the aorta, the left suprarenal gland and the upper pole of
the left kidney. The tail lies against the hilum of the spleen in front
of the left kidney. The pancreas forms part of the ‘stomach bed*, and
the stomach lies anterior to it.

The pancreatic duct starts in the tail of the gland and runs to the
right, through the entire length of the gland, to enter the duodenum
in company with the common bile duct at the duodenal papilla.

The structure of the pancreas. The pancreas is both a secreting gland
of the alimentary system whose cells discharge their secretion, pan-
creatic juice, into the pancreatic duct and it is also a gland of
internal secretion for it contains tissue known as the islets of Langer-
hans which secrete insulin.

The functions of the pancreas are to produce an internal secretion
known as insulin which is discharged directly into the blood stream,
and an external secretion known as pancreatic juice which is trans-
ported to the bowel in the pancreatic duct. These two activities are
entirely separate. Insulin is mac^e in parts of the gland known as the
islets of Langerhans and plays an essential part in carbohydrate meta-
bolism (see p. 207). The action of pancreatic juice has already been
described (seep. 189).

Pathological considerations 265

Pathological Considerations

The oesophagus may be narrowed by stricture formation due to
scarring or cancer. Failure of relaxation of the lower end is called
achalasia of the cardia or cardiospasm.

The stomach is frequently affected by peptic ulceration and
cancer.

The duodenal cap is frequently affected by peptic ulceration and
scarring of the pylorus or duodenal cap resulting from chronic
ulceration [pyloric stenosis) may interfere with the emptying of the
stomach.

The small intestine is rarely affected by cancer but may be
obstructed by adhesions or by its passage through a hernial orifice, etc.

An abdominal hernia occurs when intra-abdominal contents
pass through points of weakness in the abdominal wall by which they
are normally confined, for example the femoral and inguinal canals
and less commonly the diaphragm. If the structure which herniates
(e.g. intestine) has its blood supply constricted it is said to be
strangulated and it may become gangrenous.

Small outpouchings of the wall of the alimentary canal called
diverticula may occur, t|ie commonest site for them is the large
intestine where they may become inflamed, a condition known as
diverticulitis,

'Fhe colon is a frequent site for the occurrence of cancer. It may
also be affected by a distressing complaint called ulcerative colitis in
which the mucous membrane ulcerates.

The gall-bladder may become inflamed — cholecystitis y or it may be
the site of stone formation — cholelithiasis. Stones may migrate and
block the common bile duct resulting in jaundice, in which condition^
the bile pigments accumulate in the blood.

Definitions

Oesophagoscopy, gastroscopy and sigmoidoscopy \ the passage of an
instrument for the purpose of viewing the interior of the oesophagus,
stomach and sigmoid colon respectively.

Gastrostomy, ileostomy and colostomy: the making of an opening of a
temporary or permanent nature into the stomach, ileum or colon
respectively (-ostomy = making a hole into).

Gastrectomy and colectomy, cholecystectomy : the removal of part or the
whole of the stomach, colon or gall-bladder (-ectomy = removal of).

Gastro-enterostomy: the making of an opening between the stomach

2o6

Nutrition and metabolism

and the upper small intestine for the purpose of by-passing the
duodenum.

II

NUTRITION AND METABOLISM

FOOD

Food provides the body with material for growth and for replace-
ment of tissue suffering from the effects of wear and tear; it also
provides energy for the performance of work.

The essential constitutenls of food are water, proteins, fat, carbo-
hydrates, salts and vitamins. The process of assimilating food re-
quires its ingestion, mastication (chewing), digestion and absorption
and the elimination of indigestible or unabsorbable material (de-
faecation). Certain substances such as water, mineral salts and
glucose can be absorbed through the intestinal wall unchanged but
others require to be digested.

Nearly three-quarters of the body weight is due to water i.e. in an
average man there are about 50 litres (no lb.) or 88 pints of water.
About three-quarters of the water of the body exists within the cells
of the tissues and the remainder is found in the blood plasma, lymph
and tissue fluid. Water plays many roles in the body, and it forms
the vehicle in which secretions arc dissolved. Many .salts are dis-
solved in it and these play an essential part in many vital processes
and render possible osmosis by which fluid and metabolites traverse
cell membranes, etc. There is a balance between the intracellular
and extracellular fluid which is constant in health and is maintained
in large measure by the action of the kidneys in controlling the
output of fluid and of certain mineral salts which are responsible for
the osmotic pressure of the body fluids. Water is, of course, taken in
as fluid or in food and some is formed in the body by chemical
reactions; it is eliminated from the body by the kidneys, lungs, skin
and bowel.

When the osmotic pressure of the body fluids is disturbed because
of kidney disease, intestinal disease, etc. fluid may collect in the
tissues [oedema) and in the pleural and pericardial spaces and peri-
toneum producing pleural and pericardial effusions and ascites
respectively.

Digestion is the process of conversion of food into substances which
can be absorbed through the intestinal wall. This usually involves
the breaking down of large molecules into smaller ones.

NUTRITION AND METABOLISM

207

Proteins are nitrogenous containing foods such as meat, eggs, cheese
etc., and their chief use is in body-building. During digestion
proteins are broken down into peptones and amino-acids.

Fats are of animal or vegetable origin and, with carbohydrates,
are sources of energy. Animal fats also provide the body with
vitamins A and D. During digestion these arc broken down into
fatty acids and glycerol.

Carbohydrates such as starch and sugars are, like fats, non-nitrogen-
ous foods whose chief function is to provide energy. In the process of
digestion they are converted into glucose.

Salts are required for the formation of bone, the production of
haemoglobin and the maintenance of the correct chemical com-
position of the tissue fluids.

Vitamins are complex substances which are required in very small
amounts for a variety of essential purposes. The functions of the
vitamins are most easily studied by observing the effects of depriva-
tion. Thus lack of vitamin C produces scurvy, lack of Vitamin D
produces rickets and lack of vitamin E is one of the causes of sterility.

SUMMARY OF DIGESTION

Site

Secretion

Enzyme

Action

Mouth
(page 178)

saliva

ptyalin

starch -►glucose

Stomach
(page 187)

gastric juice

hyrochloric ^
acid >

pcp.sin J

rennin

- proteins -► peptones

curdles milk

Duodenum
(page 189)

bile and

pancreatic

juice

amylase

trypsin

lipase

starch -►glucose
proteins -► peptones
fats -►fatty acids
and glycerol

Jejunum
(page 189)

succus

entericus

erepsin

other

enzymes

peptones -► amino-
acids

sugars -♦glucose,
etc.

2o8

METABOLISM

METABOLISM

Metabolism has already (p. 5) been defined as the chemical pro-
cesses by which food is converted into energy or protoplasm and it
has been described as consisting of anabolism and catabolism^. During
the period of growth anabolism exceeds catabolism but in an adult
in normal health they balance each other and if anabolism exceeds
catabolism there will be a tendency to put on weight.

The energy requirements of the body are usually expressed in
Calories* and the total requirements of the body vary with the
amount of physical exercise the individual takes. Adults require
from 2500 (e.g. a housewife or sedentary worker) to 4000 Calories
(e.g. a man doing heavy manual work) per day. When the body is at
rest, e.g. during sleep, energy is required for vital processes such as
the maintenance of body temperature, the beating of the heart, etc.
These minimal metabolic requirements are called basal metabolism.
A normal diet must supply enough energy for basal metabolism as
well as for growth, physical exercise, etc., and it should be balanced
so that the proportions of protein, fat and carbohydrate are approx-
imately one-sixth, one-sixth and two-thirds respectively. The actual
amounts are calculated from a knowledge of the energy value of
these constituents of the diet. Thus for every i g. of protein or
carbohydrate fully oxidized 4 Calories are produced and for every
I g. of fat fully oxidized the yield is 9 Calories. The rate at which
Calories are required for basal metabolism (the basal metabolic rate)
is under the control of the thyroid gland; it is increased in fever and
in cold weather and is relatively higher in childhood. The basal
metabolic rate can be measured and it provides a method of
investigating the activity of the thyroid gland.

* 1 calorie is the amount of heat required to raise i ml. of water 1'^ centigrade.
This is a very small unit of heat and in connection with metabolism and dietetics a
larger unit is required. Such a unit is the Calorie (large G) which is the amount of
heat required to raise i litre 1° C., i.e. i Calorie =? 1000 calories.

14

The Urinary System

Waste products are eliminated from the human body by the
kidneys, the skin, the lungs and the bowel. The k idneys are the
secretory glands of the urinary system, the u reters con vey the urine
from the kidneys to the bl adder w here it is stored, and from which it
is periodically voided by being discharged through the urethra.

THE KIDNEYS

I’hc kidneys lie behind the peritoneum on the posterior ab-
dominal wall. Each kidney is 4^ inches (12 centimetres) long, 2
inches (5 centimetres) v^e and i inch (2.5 centimetres) thick and
has a convex lateral surface and a concave medial one. The medial
surface contains the hilum through which the renal vessels, the
lymphatics and the ureter pass and each kidney also has an anterior
and a posterior surface and an upper and a lower pole. The hilum
lies opposite the first lumbar vertebra and the right kidney usually
lies a little lower than the left (see p. 271).

The medial border of the kidney shows a deep recess, the renal
sinus, into which the hilum leads. The renal sinus contains the ^
major and minor calyces’, the former arise from the upper expanded
portion of the ureter called the pelvis and the latter arise from the
major calyces. About three or four minor calyces usually arise from
each major calyx.

At the upper pole of each kidney lies the suprarenal gland. The
anterior surface of the right kidney is related to the liver, the duo-
denum and the hepatic flexure of the colon. On the left side the
anterior surface is related, from above downwards, to the stomach,
the spleen, the tail of the pancreas, the jejunum and the splenic
flexure of the colon.

Structure of the Kidneys

The kidneys are enclosed by a fibrous capsule which is surrounded

209

210

THE URINARY SYSTEM

by perirenal fat. If the kidney is divided vertically from side to side
it will be seen to consist of a reddish-brown outer part, the cortex^ and
a paler inner portion, the medulla, which is composed of a scries of
pyramids. The apex of each pyramid projects into a minor calyx

Biadder (opened)

Fig. 14.1 The kidneys, ureters and bladder.

where it produces a prominence called a papilla and there arc
usually from one to three papillae in each minor calyx.

Microscopic examination shows that:

I . The cortex consists of large numbers of renal (or Malpighian)
corpuscles and the tubules leading from them.

THE KIDNEYS

21 I

Renal sinus
Renal artery
Renal vein

Pelvis of ureter
Ureter

Minor

calyx

Fig. 14.2 A sagittal section through tlie kidney.

Efferent Arteriole
Afferent Arteriole

Glomerulus

I Epithelium of
Bowman's
Capsule

Tubule

Fig. 1.4.3 ^ Malpighian body — highly magnified.

Cortex -{

Glomerulus

Bowman’s Capsule
Ist Convoluted
Tubule

2nd Convoluted
Tubule

Medulla

Pyramid

-Loop of Henie

Collecting

Tubule

Surface of
Pyramid

Jig. 14.4 Diagram of a kidney tubule.

212

THE URINARY SYSTEM

,The renal corpuscles, which are about 0.2 mm. in diameter, are
'filters for the extraction of fluid and dissolved material in the blood.
They are composed of a central tuft of capillaries, the glomerulus^
which invaginates an epithelial sac from which the uriniferous tubule
leads. The tubule takes a winding course before finally jolhing the
collecting tubules in the medulla.

2. The pyramids of the medulla are composed of the collecting
tubules which drain the urine from the tubules leading from the
renal corpuscles. They open into the minor calyces on the surface of
the papillae.

The kidneys are supplied with blood by the renal arteries, which
are branches of the abdominal aorta and arise at the level of the
first lumbar vertebra.

The Ureters

Each kidney is connected to the bladder by a ureter which is a
muscular tube about 1 0 inch es (25 centimetres) long. At the upper
end is the funncl-s haped^^g/^jr of the urete r (or kidn^) and below
this the ureter consists of abdo minal and pelvic portio ns.

The abdominal portion runs down on the psoas m uscle behindjhc
peritoneum and crosses the comm on iliac vessels to enter the pelvis.
The pelvic portionTurns medially and reaches the bladde r. In th e
female the lower end of the ureter is cl ose to the cervix of theuteru s.

Structure of the ureter. The ureter is principally composed of un-
st riped mu scle. Externally there is a fi brous tissue coat and internal ly
is the mucous membrane which is composed of transitional cell

c pithcli uin--

THE URINARY BLADDER

The urinary bladder lies in the pelvic cavity behind the pubes and
pubic symphysis. When empty it is compressedj y the weight of ^thc.
abdominal organs above it but as it fills it becomes ovoid in shape. In
infancy and childhood, because of the relatively small size of the
pelvic cavity, the bladder lies at a higher level.

The bladder is covered above by peritoneum and the superior
surface in the male is thus separated from the pelvic colon and
ileum, coils of which rest upon it. In the female the superior surface
is related to the body of the uterus and the uterovesical pouch of
peritoneum.

Below the bladder in the male is the prostate gland and in the

THE URINARY SYSTEM

213

female the m^uscles of the pelvic floor and urethral sphincter. The
inferolateral “Aspects of the bladder are related to the side walls of
the pelvis; posteriorly in the male are the seminal vesicles and the
rectum and, in the female, the vagina.

The bladder is a muscular organ lined by mucous membrane; it is
capable of containing about | of a pint (400 cubic centimetres) of
urine. There are three openings into the bladder, one for each
ureter and one for the urethra. The latter is surrounded by the
internal sphincter. The triangular area between the urethra and the
ureteric orifices is called the trigone and the mucous membrane here
is always smooth whereas in the rest of the organ in the empty state
it is thrown into folds.

The function of the bladder is to store and to expel urine.

The blood supply is derived from the internal iliac (hypogastric)
artery.

The lymphatic drainage of the bladder has been dealt with else-
where (p. 165).

THE URETHRA

The male urethra formjspart of the reproductive system as well as
being the conduit from the bladder. It is about 7^ inches (19 centi-
metres) long and is divisible into three parts:

1 . The prostatic urethra. This is about i J inches (3 centimetres) long
and is surrounded by the prostate gland ; the ejaculatory ducts open
into its floor.

2. The membranous portion. This is the shortest portion being about
J of an inch (1.75 centimetres) in length and is very frequently
damaged in crushing injuries to the pelvis and in falls astride un-
yielding objects.

3. The penile portion. This is about 5 inches (12.5 centimetres) long
and is surrounded by the corpus spongiosum (p. 221 j.

In the female the urethra is about inches (4 centimetres) in
length and lies anterior to the vagina.

^^nctions of the Kidneys

The kidneys are concerned with :

1 . The excretion of water.

2. The excretion of waste products such as urea and uric acid.

3. The control of the alkalinity of the blood.

4. The excretion of drugs, toxins and even bacteria (e.g the
kidneys can excrete typhoid bacteria).

THE URINARY SYSTEM

214

■ The kidneys perform these functions by producing urine which
consists essentially of water, salts and nitrogenous matter. The water
is derived mainly from that taken in by mouth but some is formed
as an end-product in the metabolism of protein, fat and carbo-
hydrate. •

The nitrogenous constituents of urine such as urea, uric acid,
etc., are derived partly from the breakdown by the liver of the
amino-acids from the protein of the food and partly from the tissues
as a result of catabolism.

Bladder

Vas

Ureter

Seminal

vesicle

Prostate

rig. 14.5 The structures at the base of the inalc bladder seen from

behind.

The kidneys play a large part in regulating the alkalinity of the
blood by varying the amount of acids and acid salts they excrete in
the urine. They are also of great importance in controlling other
chemical constituents of the blood and they do this by excreting the
excess when one of them rises above the ‘renal threshold’. Below this
threshold the substance is conserved in the blood and not excreted
by the kidneys.

The Formation of Urine

Urine is formed by filtration through the epithelium covering the
glomeruli; this process depends on the blood pressure and on the

RADIOGRAPHIC APPEARANCES 215

osmotic pressi^ of the blood itself. The filtrate passes from the renal
"corpuscle into the tubule, becoming concentrated during iCS passage
by the absorption of water from it and receiving certain substances
from the blood which are secreted by the cells of the renal tubules.
It is then discharged from the collecting tubules into the minor
calyces and propelled into the bladder by peristalsis (p. 197) passing
through the major calyces, the pelvis and the ureter of each side.

The volume of urine secreted daily depends on the fluid intake
and the amount of fluid lost by other routes, such as perspiration
and breathing. It is about 2^ pints (2 litres).

Micturition

Urine is stored in- the bladder and is voided at intervals by the
reflex act (p. 250) of micturition which consists of relaxation of
the sphincter of the urethra and contraction of the musculature of
the bladder. This reflex is under conscious control after infancy.

The Radiographic Appearances of the Urinary Tract

The urinary tract may^be examined by radiography without the
use of contrast media (see Fig. 13.13).

Various contrast methods may be employed but it is only pro-
posed to describe the appearances seen when one of these methods,
excretion urography, is used. In this examination an aqueous
iodine-containing compound is injected intravenously and is
excreted and concentrated by the kidneys, thus rendering parts of
the urinary tract opaque to X-rays.

Excretion Urography

In addition to the features seen in the radiograph of the abdomen,
excretion urography will demonstrate the pelvis of the ureter and
the major and minor calyces of each side, the ureters and, when
sufficient opaque medium has been excreted, the bladder. The
ureters are superimposed on the shadows of the lumbar transverse
processes and they are then seen to cross the sacro-iliac joints and
to run parallel with and about | of an inch (2 centimetres) from the
inner wall of the pelvis. At the level of the ischial spine they turn
medially to enter the bladder.

There are three constrictions normally present in the ureter.
The first of these is at the upper end of the abdominal portion at its
junction with the pelvis (of the ureter), the second is at the level of

2i6

THE URINARY SYSTEM

Fig. 14.6 Radiograph of the abdomen of a child with the urinary tract
opacified following the injection of an iodine-containing preparation.

the brim of the pelvic cavity and the third is at the junction of the
ureter with the bladder. Between these constrictions the ureter
widens out forming the two so-called ureteric spindles.

Pathological Considerations

Patients with disorders of the urinary tract frequently complain of
one or more of the following symptoms:

PATHOLOGICAL CONSIDERATIONS 217

Frequency^ micturition — often due to infection or prostatic
enlav^^ent.

Dysuria — painful micturition.

Haematuria — passage of blood in the urine.

Pyuria — pus in the urine.

Renal or ureteric colic — acute pain often due to the presence of a
small stone in the pelvis or ureter.

Incontinence - inability to control the emptying of the bladder
often as a result of nervous disease.

Conditions which a radiographer may come across in her work
include the following:

Nephritis ~ an inflammatory condition of the kidneys which
may become chronic and be attended by grave consequences.
Uraemia — the accumulation of nitrogenous waste products in
the blood usually due to renal failure.

Pyelitis — inflammation of the pelvis and ureter.

Cystitis -- inflammation of the bladder.

Hydronephrosis * dilatation of the pelvis and calyces usually due
to a partial obstruction to the ureters or urethra.

Stone formation — nefihrolithiasis or calculus disease is common
in hot climates. Stones which contain calcium are often visible
in radiographs.

Cysts may occur in the kidney and if multiple they may be
examples of a developmental abnormality called polycystic
kidneys.

Tumours of the kidney are usually either potentially or actually
malignant. The hypernephroma is met with in adults and is often
responsible for haematuria but Wilm’s tumour (nephroblastoma) ^
is the type which affects young children.

15

Reproductive System

MALE GENITAL ORGANS

The male organs of generation are :

1. The two testes.

2. The two epididymes.

3. The two seminal ducts.

Bladder Prostate Vesicula seminalis

Symphysis

pubis

Membranous

urethra

Corpus

spongiosum

Corpus

cavernosum

Clans penis

Fossa

termlnalls

Rectum

Ext.

sphincter
of anal
canal

Anal canal

Testis Bulb of penis

Fig. 15.1 Sagittal section of the male pelvis and external genital organs.

4. The two seminal vesicles.
5^ The prostate gland.

6. The penis.

218

REPRODUCTIVE SYSTEM

219

THE TEST^ (sing, testis)

The-tcrtS are oval in shape and lie on each side of the scrotum in
which they are suspended by the spermatic cords. They are abdom-
inal organs until the seventh month of intra-uterine life when they
pass into the scrotum. They are composed of finely coiled tubules,
the seminiferous tubules^ which are enclosed in a fibrous capsule, the
tunica albuginea. A double layer of serous membrane called the tunica
vaginalis separates the testis from the scrotum in the same way as a
double layer of pleura separates the lungs from the chest wall. The
spermatozoa and the fluid in which they are discharged constitute
the seminal fluid or semen.

The function of the testes is to produce the male sex cells, the
spermatozoa (p. 7), and an internal secretion, testosterone, which is
responsible for the secondary sexual characteristics.

The lymphatic drainage has already been considered J^age 165).

THE SCROTUM

THE EPIDIDYMES (sing, epididymis)

These are two crescent-shaped structures, each lies on the postero-
lateral aspect of the testis and is composed of a tortuous tube about

220

REPRODUCTIVE SYSTEM

l8 feet in length when unravelled. They transmit seminal fluid
from the testes to the seminal ducts.

THE SEMINAL DUCTS (Vasa deferentia, sing, vas deferens)

The seminal ducts begin at the lower poles of the epididymes and
run with the spermatic cords through the inguinal canals into the
pelvis. They join the ducts of the seminal vesicles to form the
ejaculatory ducts which open into the prostatic urethra.

'5'3 A demonstration of the left ejaculatory duct, seminal
vesicle and part of the vas deferens (seminal duct). The course of the
vas within the scrotum is not, of course, shown.

THE SPERMATIC CORDS

Each consists of the extra-abdominal part of the vas deferens, the
testicular artery, a plexus of veins, the testicular lymphatics, a
muscle known as the cremaster which helps to suspend the testis and
fibrous coverings derived from the abdominal wall.

THE SEMINAL VESICLES (See Fig. 14.5)

These glands lie on the posteroinferior aspect of the bladder and
their secretions are discharged via the ejaculatory ducts into the
prostatic urethra (p. 213).

REPRODUCTIVE SYSTEM

221

THE PROS^TE GLAND

Thi»-rfc?" 5 i single midline structure usually described as being
chestnut-shaped and it surrounds the upper part of the urethra
(Fig. 1 5.1) lying immediately distal to the base of the bladder. It
produces a secretion which, like that of the seminal vesicles, is
mixed with the seminal fluid in the prostatic urethra.

. THE PENIS

This is the organ by which the semen is deposited in the female
genital tract and it is attached at its base to the ischium and pubis.
It is composed of three erectile structures, the two corpora cavernosa
and the corpus spongiosum which become rigid and erect when en-
gorged with blood. The urethra traverses the corpus spongiosum
and opens externally on the glans^ as the slightly enlarged distal
portion of the penis is called. The prepuce or foreskin is a sheath of
skin which partially covers tlie glans.

FEMALE GENITAL ORGANS

The female organs of ^^ncration are :

{a) Internal organs

1. The two ovaries.

2. The uterus.

3. The two uterine (Fallopian) tubes.

4. The vagina*

{b) External organs

1 . The vulva.

2. The mammary gland.

THE OVARIES

These are oval structures, i inch (2.5 centimetres) in length and
inch ( I centimetre) in width, lying on the lateral walls of the pelvic
cavity on either side of the uterus and suspended from a peritoneal
sheet, the broad ligament of the uterus, which stretches laterally from
the uterus to reach the pelvic wall on either side and below. In the
free upper border of the broad ligament run the uterine tubes (see
below) and the ovaries are suspended from its posterior surface. The
ovarian and uterine blood vessels and lymphatics run between the
layers of the ligament.

222

REPRODUCTIVE SYSTEM

Structure of the ovary. Each ovary consists of fibroua,jtissue in which
lie several thousand islands of cells derived during life from
the germinal epithelium, which lies immediately beneath the fibrous
tissue capsule. These islands of cells are known as Graafian follicles and
each contains an ovum or egg cell and secretes a hormone, oestrogen
(see p. 239). Every month a Graafian follicle migrates to the peri-
phery of the ovary and ruptures, ejecting the ovum which it contains
into the peritoneal cavity in the neighbourhood of the internal open-
ing of one of the uterine tubes. After discharging the ovum the follicle

Recto-uterine

'pouch

Post, vaginal

fornix

Rectum

External
‘sphincter
of anal canal

Fig. 15.4 Sagittal section of the female pelvis.

increases in size and becomes yellow, forming the corpus luteum.
Unless pregnancy occurs this corpus luteum degenerates but if
pregnancy should take place the corpus luteum increases in size and
produces a hormone (p. 239) called progesterone which is essential for
the retention of the foetus in the uterus.

THE UTERUS

The uterus or womb when seen from the front is a pear-shaped
organ measuring 3 inches (7.5 centimetres) long and 2 inches (5
centimetres) wide. It is flattened from front to back measuring about
I inch (2.5 centimetres) in thickness and it is divided into three parts,
the fundus, the body and the cervix. It is situated between the

REPRODUCTIVE SYSTEM 223

bladder and rectum and is covered anteriorly and posteriorly by
pcritoimyrvr^hich forms a double fold on either side known as the
broad ligament of the uterus. On either side of the fundus are the upper
corners or fornices (sing, fornix) from which the uterine tubes run
laterally in the upper parts of the broad ligaments. The two round
ligaments also run in the broad ligaments and help to support the
organ.

Fundus of uterus Uterine tube

Fig. 13.5 Diagram of a specimen showing the uterus, the uterine
tube, the ovary and adjacent structures of the right side, seen from
'T' behind.

The lowest portion of the uterus is the cervix or neck and its lower
end, the external os, projects into the vault of the vagina. The cavity
of the cervix is called the cervical canal and the internal os marks the
junction of the uterine cavity with that of the cervix.

The uterus is composed principally of muscle, the myometrium, and
its interior is lined by a mucous membrane known as the endometrium.
'Fhis is smooth in appearance in the body of the uterus but ridged in
the cervix.

The uterus derives its blood supply from the uterine artery on
each side which arises from the internal iliac (hypogastric) artery.
I'hese arteries cross the pelvic floor and run upwards in the broad
ligament; near the cervix they are in front of the ureter and because
of this relationship the ureter can be damaged during operations on
this part of the uterus.

The lymphatic drainage of the uterus and cervix is considered
elsewhere (p. 165).

Tho function of the uterus is, of course, to provide suitable sur-
roundings for the development of the foetus and this necessitates a
complex series of changes in the endometrium to maintain its state of

22.

REPRODUCTIVE SYSTEM

Vestibule

Meatus of
Urethra

Anus

Fig. 15.fi The external genital organs of the female.

preparation for such an event (see Menstruation and Ovulation
page 226).

THE UTERINE TUBES (the Fallopian tubes)

These are hollow muscular tubes lined by ciliated columnar
epithelium, they are about 4^ inches (i i centimetres) in length and
they conduct the ovum into the uterus. Fertilization of the ovum by
the spermatozoon usually occurs in them. The tubes run in the upper
margin of the broad ligaments and are divisible into an intramural
portion in the walls of the uterus, a narrow isthmus and a wider
ampulla which leads to the infundibulum from which a number of

Fourchette

Navicularis

Perineum

REPRODUCTIVE SYSTEM

225

processes or fim^iae project. The ovary lies close to the inrundibulum
and the presumably help to direct the ovum into the tube.

THE VAGINA

The vagina runs from the external os of the cervix to the vulva.
It is lined by skin moistened by the mucous glands of the cervix,
which projects into the upper part or vault. There is a recess or
fornix surrounding the cervix which is largest posteriorly where it is
called th^ posterior fornix and above this is the lowest part of the
peritoneal cavity, the recto-uterine pouch (of Douglas) (p. 185).
The bladder and urethra are anterior to the vagina and the rectum
is posterior to the upper part of it. The lower part of the vagina is
separated from the anal canal by the perineal body — a mass of
fibrous and muscular tissue which is capable of stretching greatly
during labour. The lower end of the vagina is partially closed by the
hymen in the virgin state.

The lymphatic drainage has been dealt with elsewhere (p. 165).

THE VULVA

The vulva is a cleft through which the urethra and the vagina
open. It is bounded on either side by the labia mqjora which run from
the mans veneris anteriorly to the perineum, the region between the
vulva and the anus, posteriorly. The mons veneris lies over the
symphysis pubis and bears hairs after puberty. At the posterior end
of each labium majus is a mucous gland, Bartholin’s gland.

The labia minora lie medial to the labia majora and meet anteriorly
forming the prepuce of the clitoris, a small erectile structure related
embryologically to the penis. The labia minora meet posteriorly in a
fold called thefourchette. The opening of the urethra is anterior to the
vaginal orifice.

THE BREASTS

These are accessory organs of reproduction and develop fully in
the female after puberty. They are circular in outline and contain
much fat so that they vary greatly in size from individual to indivi-
dual. They lie between the lateral border of the sternum and the
axilla on the pectoralis major muscle from the level of the second rib
above to the sixth rib below.

The breast consists of a series of lobules from each of which a *
lactiferous duct runs; after dilating to form the ampulla each duct

226

REPRODUCTIVE SYSTEM

converges on the nipple and opens on its surface.vJhe nipple is a
small raised area surrounded by the pigmented aremlh^

The lymphatic drainage has been dealt with elsewhere (p. 164).

Axillary tail ■

Fibrous septa
and fat

Nipple

Areola

Lactiferous ducts

Fig. 15.7 Diagram to show the structure of right breast.

MENSTRUATION AND OVULATION

The endometrium undergoes a complicated cycle of changes
every month in preparation for the possible arrival of a fertilized
ovum. These changes start at puberty and continue until the climacteric
or menopause which occurs between 45 and 50 years of age ; after it the
woman is unable to reproduce. The cycle is controlled by hormones
(Chapter 16) secreted by the ovaries and the pituitary gland and as
the cycle lasts approximately i month it is called menstruation.

There are four stages in the menstrual cycle. The resting stage lasts
.about 10 days; it occupies the middle of the cycle and ovulation (the
shedding of the ovum by the ovary) occurs during it. This is followed
by the premenstrual (constructive) stage which lasts about 6 days and
is accompanied, by hypertrophy and engorgement of the endo-
metrium. Then some of the epithelium is shed and bleeding occurs
during the 5 days or so of the destructive stage which causes the
menstrual flow. The last stage, that of repair follows and occupies
about 7 days.

The object of menstruation is achieved if pregnancy occurs and
the developing corpus luteum of pregnancy suppresses the men-
strual cycle. Menstruation does not usually recommence until
lactation has ceased.

REPRODUCTIVE SYSTEM

227

Fig. 15.8 Diagrain to illustrate the menstrual cycle.

PREGNANCY

The consequences of fertilization of the ovum have already been
briefly described (p. 7). Certain maternal changes occur during
pregnancy and amongst these are increase in the size of the breasts
and pigmentation of the areolae. The uterus enlarges and estimation
of the height of the fundus by abdominal palpation is an approxi-
mate method of assessing <|he age of the foetus. During the latter part
of pregnancy the pelvic ligaments undergo softening so as to allow
the sacro-iliac joints and symphysis pubis to stretch during labour.
Approximately 280 days after conception uterine contractions
commence, the cervix and vagina progressively dilate, the perineum
stretches, the amniotic fluid surrounding the foetus drains away and
the birth of the child follows. There is usually a short delay before
the placenta is expelled so the umbilical cord which attaches the
infant to the placenta is divided between ligatures.

Lactation ^

As term approaches a clear fluid called colostrum is secreted by the
breast and this is followed a few days after delivery by the secretion
of milk. The pituitary gland stimulates the breast into activity but
the continued secretion of milk also requires regular emptying of the
lactiferous ducts. .

The Radiographic Appearances of the Female Genital

Tract

The female genital tract may be demonstrated by radiography
after the instillation through the external os of iodized poppy-seed

228

REPRODUCTIVE SYSTEM

oil or viscous iodine preparations (hysterosalpiny()graphy). The
cervical canal, the uterine cavity and the various parts he uterine
tubes will be demonstrated and patency of one or both uterine tubes
will be shown by the entry into the peritoneal cavity of some of the
opaque medium. ^

Isthmus
of right
uterine
tube

Fundus
of uterus

Left

uterine

tube

Internal

Cervix

f’ig- *5-9 Radiograph of the female genital iract after the injection of an opaque
medium. ('I’he uterus normally is not flexed to the left as in this subject.)

Pathological Considerations of the Male Genital Tract

Radiographic investigation of the male urethra [urethrography) may
be required in the investigation of congenital urethral valves (usually
in infancy) and strictures which may be traumatic (e.g. following
fractures of the pelvis) or due to infection (e.g. gonorrhoea).

The prostate is liable to become enlarged in the elderly by a non-
malignant condition which may constrict the urethra. The kidneys
may be damaged by the resulting obstruction to the emptying of the
bladder and excretion urography may be required in the planning
of surgical treatment.

The prostate may also be the site of carcinoma and this tumour,
and the secondary deposits which tend to attack the skeleton, are
often dramatically improved by treatment with female sex hormone.

The testis may be the site bf malignant tumour formation [semi-
noma in young adults, teratoma in older patients) and because of its

REPRODUCTIVE SYSTEM

229

lymphatic dra^ .fage nodes of the aortic group may become involved
and repn’ creatment.

Pathological Considerations of the Female Genital Tract

Gynaecological disorders are often associated with disorders of
menstruation and a number of terms are used to describe these.

Painful menstruation is called dysmenorrhoea. Failure to menstruate
is called amenorrhoea and it is, of course, a normal state during
pregnancy. Excessive blood loss during menstruation is called
menorrhagia.

Inflammation of the uterine tubes is called salpingitis and preg-
nancy occurring in a uterine tube instead of in the uterus is called a
tuba! (or ectopic) pregnancy.

Radiographic study by hysterosalpingography may be required in
cases of sterility and infertility to determine whether the tubes. are
blocked or patent.

Radiography of the pregnant uterus may be called for in the
diagnosis of twins, foetal abnormalities, foetal maturity, placental
localization, etc., and the diameters of the pelvis may be measured
by radiological pelvimetry.

Radiography has an important part to play in placental localiz-
ation because a placenta implanted in the lower part of the uterus
may obstruct labour and cause dangerous bleeding. The placenta
may be localized by plain radiography or by arteriography.

The uterus may develop tumours of the myometrium. These arc
usually non-malignant and are known as fibroids. Cancer of the uterus
may occur and it arises in the endometrium cither of the body or the
cervix of the organ. Cancer of the cervix is particularly prone to involve
the ureters when it spreads locally, so excretion urography may be
called for in the planning of treatment.

The ovary is liable to develop cysts which sometimes attain great
size and tumours which may be innocent or malignant.

The breast is liable to a number of diseases. These include chronic
mastitis, a^ non -malignant proliferation of tissue with cyst formation,
and carcinoma which is, of course, all too common in women of the
fourth and fifth decades. It may be treated by radiotherapy alone
or by a combination of radiotherapy and surgery.

i6

The Endocrine System

The endocrine system is made uj3 of a number of glands whose
secretions or hormones pass directly into the blood stream. The
ductless glands are not in fact the only sources of hormones as certain
parts of the alimentary tract also produce hormones.

The hormones are often called chemical messengers and becatjse
they are carried round in the blood stream they are likely to produce
very widespread effects. Their action may be studied by observing
the results of pathological oversecretion ancf undcrsccretion of the
glands which produce them, and by observing the effects of giving
the dried extract of the gland or the synthetic hormone to human
beings.

Some glands function both as glands of external secretion and as
ductless glands. These functions are usually quite distinct and un-
related; for example, the external secretion of the pancreas is the
pancreatic juice and its internal secretion is insulin.

THE PITUITARY GLAND

The pituitary gland is of great importance in the body for, in
addition to producing hormones which have a direct effect on tissues,
it produces a number of hormones which exert a controlling in-
fluence on other endocrine glands. The pituitary gland has been, in
fact, very aptly termed ‘the conductor of the endocrine orchestra’.
It is a single midline structure about i centimetre in diameter lying
in the sella turcica (p. 41) and connected to the brain by a stalk
through which nerve tracts run to that part of the brain known as
the hypothalamus. The gland is closely related in position to the
optic nerves which join to form the optic chiasma just above and
anterior to it. This relationship is important in that tumours of the
pituitary gland may exert pressure on the optic nerves and the
chiasma leading to visual disturbances including blindness.

The pituitary gland is composed of an anterior and a posterior
lobe, both of which are hormone-secreting, and these are separated
by a middle part which does not appear to secrete any hormones.

230

THE PITUITARY GLAND

231

Third Ventricle

Stal*’ o'

tituitar'y Gland

Anterior
Lobe of
Pituitary

Sphenoid Air Cell [

Subarachnoid

Space

Posterior Lobe
o Pituitary

Pons

Medulla

Base of
Skull

Foramen Magnum
Fig. 1 6. 1 Diagram illustrating the pituitary gland.

The function of the anterior lobe of the pituitary gland is to produce
the following hormones :

1 . Growth hormone. Thijfc hormone influences the growth of tissues,
particularly the skeleton. Production of this hormone appears to
be well regulated as pathological states resulting from overpro-
duction and underproduction of this hormone are rare.

2. Thyroidrstimulating hormone {T.S.H.). "I'he thyroid-stimulating
hormone contiols the activity of the thyroid gland. A rise in the
amount of T.S.H. secreted by the pituitary results in a rise in the
amount of thyroxin secreted by the thyroid gland.

3. Adrenocorlicotrophic hormone A.C.T.H. stimulates

the cortex of the adrenal glands to secrete hydrocortisone. Alter-
ations in the amount of A.C.T.H. secreted by the pituitary result
in alterations in hydrocortisone output by the suprarenal glands.

4. Prolactin. Prolactin is only thought to be of significance in the
lactating woman in whom it is partly responsible for the production
of milk by the breast.

5. Follicle-stimulating hormone. {F.S.H.). F.S.H. in the female
stimulates the development of the Graafian follicle and stimulates
the mature follicle to produce oestrogen. In the male F.S.H. stim-
ulates the production of spermatozoa.

6. Luteinizing hormone. The luteinizing hormone in the female
stimulates the formation of the corpus luteum after ovulation and
the secretion of progesterone by the corpus luteum. In the male the

THE ENDOCRINE SYSTEM

232

luteinizing hormone stimulates the interstitial celh .of the testis to
produce testosterone. Thus the luteinizing hormone is iR^-inly con-
cerned with the production of the sex hormones whilst the follicle-
stimulating hormone is mainly concerned with the production of the
germ cells, the ova and the spermatozoa. •

The function of the posterior lobe of the pituitary gland is to produce
the following hormones :

1. The antidiuretic hormone A diuresis is the passage of a

quantity of dilute urine after drinking a large volume of fluid and as
the name suggests A.D.H. opposes the diuresis under these circum-
stances. A.D.H. plays a vital role in the control of the total amount
of water in the body. After consuming large quantities of fluid it is
usual to experience a diuresis and this occurs because under these
circumstances the secretion of A.D.H. by the pituitary /fl/Zj allowing
diuresis to occur. A.D.H. controls the output of urine by controlling
the amount absorbed by the distal tubules of the kidney. Under
conditions of water deprivation A.D.H. is secreted in large amounts
and the distal tubules absorb most of the water passing through the
kidney. Only a small amount of highly concentrated urine is passed
and thus water is conserved for use by the body. A.D.H. is also
secreted in larger amounts at night and thus the amount of urine
formed during sleep is much less than during the daytime.

2. Pituitrin. I'his is the other hormone secreted by the posterior
lobe of the pituitary gland, it is apparently less important physiolog-
ically than the antidiuretic hormone. It causes .smooth muscle such
as that of the walls of blood vessels, bowel, bladder and uterus to
contract.

Pathological Considerations

The importance of the relationship of the pituitary gland to the
optic chiasma has already been referred to.

In childhood overproduction of growth hormone results in a
young individual becoming excessively tall {gigantism) whilst under-
production results in dwarfism. Overproduction of growth hormone
in the adult produces the condition known as acromegaly. Acromegaly
is characterized by coarsening of the patient’s appearance and en-
largement and thickening of bones, particularly the mandible, and
the bones of the hands. In the advanced stage the patient is pathe-
tically grotesque in appearance. One of the effects of lack of function
by the posterior lobe is the passage of very large quantities of dilute
urine, the condition known as diabetes insipidus.

THE THYROID GLAND

233

THE THYROID GLAND

The thyroid gland is situated in the neck in close relationship with
the larynx and the upper part of the trachea at the level of the lower
three cervical and first thoracic vertebrae. It consists of two lobes
which are joined by an isthmus. The lobes are conical in shape and
lie on either side of the lower part of the larynx and the cervical
portion of the trachea anterior to the recurrent laryngeal nerves
(which supply the larynx), the parathyroid glands, the common

Internal carotid artery

Thyroid cartilage

Cricothyroid

muscle

Cricoid cartilage

Isthmus of thyroid
gland

Common

carotid

artery

R. innominate
vein

Carotid sinus

External carotid
artery

Int. jugular
vein

Lateral lobe of
thyroid gland

Inf. thyroi
veins

L. Innominate
vein

Fig. 16.2 The thyroid gland.

carotid arteries and the internal jugular veins. The isthmus lies on
the anterior surface of the trachea and intervening between the
gland and the skin are the thin pretracheal muscles and the sterno-
mastoid muscles.

The functions of the thyroid gland are concerned with iodine
whicli it extracts, from the blood, concentrates and stores. Jt pro-
duces the hormone thyroxin which it also stores so that it is for
secretion into the blood stream. As has already been indicated

Q.

234 the endocrine system

the thyroid is stimulated to secrete thyroxin into thi blood stream by
the thyroid stimulating hormone secreted by the pituitary gl^nd. The
thyroid hormone, thyroxin, exerts a controlling influence on the
metabolic rate of tissues and normal thyroid function is required for
normal mental, sexual and skeletal development. •

Pathological Considerations

Diseases of the thyroid gland arc commonly encountered in
hospital practice. Enlargements of the thyroid gland are termed
goitres; goitres are usually located in the neck but sometimes are
partially or wholly behind the sternum. The presence of a goitre in
the retrosternal position may be demonstrated radiographically.
A goitre may not be associated with any overactivity of the gland
when it is termed a non-toxic goitre. On the other hand the goitre may
be accompanied by oversecretion of thyroxin when it is termed a
toxic goitre.

Oversecretion of thyroxin produces a condition termed thyrotoxi-
cosis (hyperthyroidism). The excessive amount of circulating thyroxin
produces acceleration of the metabolic rate and this leads to
emotional disturbances, rapid heart rate, poor toleration of heat,
loss of weight and sometimes protrusion of the eyes (exophthalmos).

On the other hand undersecretion of thyroxin produces an entirely
difi’erent picture: in infancy it causes cretinism a form of mental defect
associated with dwarfism and retardation of both skeletal and
sexual development. In adults undersccrction results in myxoedema
(hypothyroidism), a condition characterized by mental apathy and
dullness, a coarsened appearance, intolerance of cold, thinning and
loss of lustre of the hair and other manifestations of the slowing down
of metabolism.

Iodine has been mentioned as an important component of tliff
thyroxin molecule- The body requires only minute quantities oT
iodine amounts which are readily obtained from the normal food-
stuffs in most areas. In certain mountainous areas the soil is poor in
iodine and consequently the diet of the inhabitants of th^e regions
.may be deficient in iodine. The result is that the* development of a
goitre during puberty is not uncommon in that region^ ]e.g. ‘Derby-
shire neck’. Only rarely, hpwever, is the . deficiency in iodine
sufficient to result in underseCretion of thyroxin. The condition can
be pcgllpted by the simple expedient .of adding .small quantities of *
iodin™^* table salt, a method which has had marked success in
Switzerland.

THE THYMUS GLAND

235

The ParathyriSid Glands

These arc small pea-like structures, usually four in number, which
are embedded, two on each side, in the posterior aspect of the lobes
of the thyroid gland. The close anatomical association of the
parathyroid glands with the thyroid gland gives them their name
but functionally they are quite distinct.

The function of the parathyroid glands is to secrete a hormone parathor-
mone which plays a vital role in the regulation of the amounts of
calcium and phosphorus in the blood and bone.

Pretracheal

Fig;, it).^ 'i raiis\crsc section of the* lower part of (he neck showing
the thyroid gland, etc.

Pathological Considerations

Conditions resulting from disordered activity of' these glands are
. rare. C^ver activity or hyperparathyroidism is associated with withdrawal
of calcium from the bones, elevation of the level of calcium in the

V -

* blood and the deposition of calcium in sites such as the kidneys and
blood vessels. I’he withdrawal of calcium from the bones may lead
tp the development of bone deformities and the occurrence of
fractures as a result of relatively minor trauma. Underactivity of the
glands or hypoparathyroidism results in a lowering of the level of
the blood caIciun^*^The main effect of the lowering of the blood
calcium ipccufj^n.ce of a form of muscle spasm known as tetany.

THE THTMUS GLAND

Ihis gland is situated in the anterior mediastinum beVBbn the
heart and great vessels behind and the sternum in front. Knowledge

THE SUPRARENAL GLANDS

236

about its function is meagre. It is relatively large in infancy but it
atrophies after puberty.

Pathological Considerations

In babies the thymus may be seen in radiographs of the chest. In
the rare disease myasthenia gravis a thymic tumour may be present ;
it may then be demonstrable radiographically and its removal may
be very beneficial.

THE SUPRARENAI. GLANDS

1 he suprarenal or adrenal glands arc situated at the upper pole
of each kidney; they are related posteriorly to the diaphragm and
anteriorly they form part of the stomach bed lying in the posterior
wall of the lesser sac of the peritoneum. The right is related anteriorly
to the inferior vena cava and the liver. Each^ gland consists of an
outer part, the cortex, which surrounds the inner part, the medulla.
The two parts of the suprarenal gland can be regarded separately
because they have a different structure microscopically and they
secrete groups of hormones with distinctly different functions. The
cortex of the suprarenal is essential to life whilst the medulla is not.

The Junction of the suprarenal cortex is to produce the following
hormones :

1. Hydrocortisone and aldosterone which affect the metabolism of
water, minerals, carbohydrate, protein and fat. Hydrocortisone is
an extremely important hormone and has a very wide use in
medicine. This is because the ‘steroid’ hormones, hydrocortisone
and its analogues, have very marked damping effect on inflammatory
reactions quite apart from their effects on metabolism. Thus the
benefit obtained in, for example, a dermatitis or an arthritis is largely
due to this damping effect on inflammation. The excretion of hydro-
cortisone is regulated by A.C.T.H. from the pituitary. The action
of aldosterone is complex and can be ignored.

2. Sex hormones^ the cortex of the suprarenal gland produces small
quantities of hormones similar to oestrogen in the female (see p. 239)
and testosterone in the male (see p. 239). These hormones are
produced both in males and females and thus there are always small
quantities of female sex hormones in the male and vice versa.

The ^up^renal medulla

The function of the suprarenal medulla is to secrete two hormones

The pancreas

237

noradrenaline anc/ adrenaline which have roughly similar actions. These
actions mobilize the body for sudden activity in response to stress,
an effect which has been termed the ‘fight or flight reaction’. The
effects produced are similar to stimulation of the sympathetic ner-
vous system, an effect which is more understandable when it is
realized that the adrenal medulla is, in fact, a part of the sympathetic
nervous system. The administration of adrenaline constricts the
blood vessels of the skin and the intestines, diverting blood to the
muscles, heart and brain, it raises the blood pressure and increases
the heart rate, dilates the pupils and the bronchi and produces a
number of other effects. These effects can be readily observed in
individuals who are alarmed and they prepare the individual to
respond more fully to the initial stimulus.

Pathological Considerations

Bilateral destruction of the cortical parts of the glands by tuber-
culosis resulting in undersecretion of cortical hormones, known as
Addison's disease^ is encountered less commonly at the present time
than formerly. Addison’s disease, if untreated, may result in death
from loss of sodium chloride in the urine and general loss of resistance
to stress and infection. Tlffe patient with classical Addison’s disease
is wasted and shows a characteristic pigmentation of the skin and
the mucous membranes.

The condition of overactivity of the adrenal glands results in
Cushing^s sjndrome. Patients with Cushing’s syndrome have a char-
acteristic obesity with particular involvement of the trunk and the
face (‘moon face’), overgrowth of hair, particularly facial hair,
hypertension and many other features.

Very rarely indeed the sex hormones are excreted in excess result-
ing usually in virilism i.e. the exaggeration of the male characteristics
so that women develop certain masculine features and boys reach
puberty at an unusually early age.

The value of cortisone in medicine has already been referred to
(see p. 236).

THE PANCREAS

The gross anatomy of the pancreas has already been described
(p. 204). It will be recalled that this is one of the glands which
produce both an external and an internal secretion. The fo?jiier is,
of course, a digestive juice which is discharged througn^^e pan-
creatic duct.

THE ENDOCRINE SYSTEM

338

The endocrine function of the pancreas is to secr<^lc insulin; this
hormone is produced by small groups of specialized cells which ar,c
scattered amongst those which arc concerned with the production
of the external secretion. These small groups of cells are termed the
islets of Langerhans and can be readily identified on microscopic
examination of pancreatic tissue.

Insulin regulates carbohydrate metabolism and is secreted in
response to a rise in the blood sugar level such as occurs during the
digestion and absorption of food. Insulin causes the liver to store
carbohydrate as glycogen (a derivative of glucose), enables the
tissues to utilize carbohydrate and promotes the conversion of car-
bohydrates to fat for storage. Insulin therefore has a tendency to
lower the blood sugar but the amount of insulin secreted is normally
well regulated and insulin secretion is curtailed if the blood sugar
falls below the average level. On the other hand insulin, given
therapeutically for diabetes mellitus can, if care is not taken with the
dosage and the diet, lower the blood sugar ^sufficiently to cause
symptoms. The patient is said to be suffering then from hypoglycaemia
and the effects arc often very bizarre. Mental symptoms are promin-
ent and may take the form of restlessness or anxiety, excitement,
apathy or ‘drunkenness’. Ifie patient may complain of hunger and
may show sweating, tremor and a raised pulse rate. If the hypo-
glycacmia is severe unconsciousness and even death may result. The
radiographer must be aware of this condition as from time to time
one encounters it in patients undergoing radiographic examination.
The treatment is the administration of carbohydrate as quickly and
as safely as possible. If the patient can swallow, glucose or cane sugar
in water must be given but if the patient is unconscious glucose must
be given intravenously. Recovery with correct treatment is prompt.

Pathological Considerations

Absolute or relative lack of insulin results in diabetes mellitus. The
patients are unable to metabolize glucose with the result that the
blood glucose level rises and glucose is excreted in the urine, where
it can easily be detected by simple chemical tests. The carbohydrates
absorbed from the gut cannot be properly utilized and the patient
loses weight and strength. Energy stores such as fat are burned up
to provide energy for the body to function but this leads to the
accumulation of organic acids, the by-products of the metabolism of
fat, in the blood. This accumulation of organic acids may be so
severe as to to cause coma. The passage of large quantities of glucose
in the urine causes a diuresis; the patients are often troubled by the

THE GONADS

239

excessive amourAs of urine they pass and the consequent troublesome
tjiirst. Resistance to infections is lowered and the incidence of
pulmonary tuberculosis is appreciably higher in diabetics. Patients
with diabetes have a tendency to develop arterial disease and this
may lead to gangrene especially of the feet.

THE GONADS

The gonads or sex glands, like the pancreas, may be regarded as
being glands which produce both external and internal secretions.
We arc only concerned with the latter in this section.

The interstitial tissue of the testis, under the stimulus of the luteiniz-
ing hormone of the anterior lobe of the pituitary gland, produces
testosterone. This is the hormone responsible for the secondary sexual
characteristics which develop at puberty and include the distribu-
tion of hair on the face and body, the distribution of subcutaneous
fat, and the changes in the voice, the shape of the pelvis and mental
attributes wliich characterize the male sex.

Oestrogen, the secretion of the (iraafian follicle resulting from
stimulation of the ovary by the follicle-stimulating hormone of the
anterior lobe of the pituitaYy gland is responsible for the secondary
sexual characteristics and the breast development which occurs in
the female at puberty. Oestrogen is also responsible for the endo-
metrial changes which characterize the destructive and reparative
stages of the menstrual cycle.

After ovulation (p. 226) the corpus luteum is responsible for the
hypertrophy and engorgement of the endometrium which occurs
during the constructive (premenstrual) phase of the menstrual
cycle. During pregnancy, however, the corpus luteum is stimulated
by the luteinizing hormone of the pituitary gland to continue the
secretion of progesterone since this hormone is essential for the reten-
tion of the foetus in the uterus. I’he corpus luteum therefore persists
throughout pregnancy.

Pathological Considerations

{^Removal of the gonads in a young individual before puberty will
result in the non-appearance of secondary sexual characteristics.
In adult life such a procedure has much less effect. It has been found
that some cases of advanced malignant disease benefit from removal
of the gonads, thus in women with advanced carcinoma of the
breast the operation of removal of the ovaries may be followed by
regression of secondary deposits.

240

THE ENDOCRINE SYSTEM

THE PINEAL BODY

This structure is usually considered with the ductless glands but it
has no known function. It is situated in the midline within the skull
between the under surface of the cerebrum and the mid-brain. It is
frequently calcified and visible in radiographs (Fig. 6.17a).

17

The Nervous System

The nervous system is a complex mechanism which regulates
many bodily activities. It consists of supporting tissue called
neuroglia and large numbers of nerve-cells^ most of which bear at least
two processes called nerve-fibres.

A nerve-cell with its fibres is called a neuron and an afferent neuron
carries information from nerve endings, such as those in the skin,
muscles and joints, to the brain and spinal cord. An efferent neuron
conducts from the brain and spinal cord impulses such as those
which cause muscles to contract and relax and glands to secrete.
The nerve-cells of the brain are situated in a superficial layer called
the grey matter and the nerve-fibres make up the white matter which
lies deep to this. In the spihal cord the grey matter lies deeply and
the white matter is superficial.

The nervous system is made up of:

(1) The central nervous system consisting of the brain and spinal
cord.

(2) The peripheral nervous system which connects the various
parts of the body with the central nervous system.

(3) The autonomic nervous system which is concerned with the
involuntary or vegetative functions of the body.

THE BRAIN

The human brain is a large and complex structure which will be
better understood if some stages in its development are briefly
described.

The nervous system develops from the ectoderm as a thickened
plate on the surface of the embryo, it then sinks below the surface
and becomes converted into a tube. Part of this tube becomes the
spinal cord, but the head-end enlarges to form the future brain and
three parts containing cavities or ventricles can be recognized : the

241

242 THE NERVOUS SYSTEM

fore-brain, the mid-brain and the hind-brain. ^The fore-brain
expands laterally on each side to form the cerebral hemispheres
which increase greatly in size and eventually envelop most of the
rest of the brain.

The chief parts of the brain may be tabulated according to their
developmental origin.

(1) The fore-brain gives rise to:

(fl) ^’he cerebral hemispheres or cerebrum.

{b) The thalamus and hypothalamus.

(2) The mid-brain gives rise to:

The cerebral peduncles.

Fig. 1 7. 1 Diagram illuslrating the left lateral asjjcc I ol the brain.

(;3) The hind-brain gives rise to:

{a) The pons.

{b) The medulla oblongata
(r) The cerebellum.

The Cerebrum

This consists of the right and left cerebral hemispheres, it is the
most conspicuous feature of the human brain and occupies the
anterior and middle cranial fossae. The surface layer or cortex
consists of grey matter which is folded into convolutions or gyri
separated by sulci ^ an arrangement which greatly increases the
andount of grey matter relative to the size of the brain. The interior
is composed of white matter and contains the lateral ventricles.

Each hemisphere is divided for descriptive purposes into frontal,

THE BRAIN

243

parietal, occipiAl and temporal lobes which take their names from
the overlying bones. A sulcus called the central sulcus separates the
frontal from the parietal lobes and runs downwards almost to the
lateral sulcus separates the temporal from the frontal and parietal

lobes. In front of the central sulcus is the motor cortex or precentral
gyrus where all voluntary movements are initiated and behind the
sulcus is the sensory cortex or postcentral gyrus where most sensory
impressions are received. T’he occipital lobe is concerned with sight;
other areas of the cortex can be mapped out where various functions
are controlled such as hearing, writing, speech, etc.

T*he functions of the cerebrum are the initiation of all volun-
tary movement, the reception of all sensory impressions and the
correlation of these activities resulting in speech, language, thought,
intelligence, memory, etc.

Central sulcus

riiiiclions in the left cerebral hemisphere.

The mid-brain consists of the cerebral peduncles and it
connects the cerebral hemispheres to the pons. Its cavity is a narrow
canal, the aqueduct.

The pons connects the cerebral peduncles to the medulla
oblongata and it also connects the two cerebellar hemispheres to
each other.

The medulla oblongata lies just in front of the foramen magnum
and intervenes between the pons and the spinal cord. There are
centres in it which control breathing, the action of the heart, the
calibre of the blood vessels and such reflex activities as swallowing

THE HEftVodS SVSTEM

244

,and vomiting, the movements of the alimentar/ canal and the
secretion of the digestive juices

The cerebellum lies in the posterior cranial fossa; its surface is
thrown into folds and it is divided into right and left lobes which
are connected by the pons. Its functions, which are* not under
voluntary control, are to co-ordinate muscular movement and to
maintain balance and equilibrium.

THE VENTRICULAR SYSTEM OF THE BRAIN

The cerebral hemispheres each contain a lateral ventricle and these
are the largest cavities within the brain. Each communicates by the
interventricular foramen with the third ventricle and each has an
anterior horn, a body, a posterior and a temporal horn. The last

Fig. 17.3 Diagram illustrating the ventricles of the brain.

of'these runs into the temporal lobe. The third ventricle is the cavity of
1fce fore-brain and lies between the two thalami; in addition to
communicating with each lateral ventricle it is joined posteriorly
by the aqueduct.

The cavities of the mid-brain and hind-brain are the aqueduct and
the fourth ventricle respectively. The central canal of the spinal cord
runs downwards from the fourth ventricle and in the roof of this
ventricle are apertures through which the cerebrospinal fluid passes
into the subarachnoid space which intervenes between the arachnoid
mater and pia mater, two of the meninges or membranes covering
the brain (p. 251). Capillary tufts called choroid plexuses project into
the ventricles from their roofs and produce the cerebrospinal
fluid (p. 252).

THE BRAIN

245

THE CRANIi¥L NERVES

There arc twelve pairs of nerves arising from the brain; some arc
afferent (sensory), some are efferent (motor) and some are mixed.

(I) The olfactory is sensory and is the nerve of smell.

(II) The optic is sensory and is the nerve of sight. It begins in the

Olfactory bulb

/

/

Optic n.

Int. carotid a.
and middle
cerebral a.

3rd n.
Masilar a

5tli n.
Cth n.
7th n.

8ih n.
nth n.

Fig. 1 7.4 The base of the brain.

retina of the eye and passes through the orbit and optic canal to
reach the interior of the skull where many fibres from each eye
cross to the opposite side at the optic chiasma and then continue on
into the brain to the occipital part of the cerebral cortex (Fig. 18.2).

(Ill) The occulomotor, (IV) the trochlear and (VI) the abducent
are all motor to the muscles of the eyeball.

246 THE NERVOUS SYSTEM

(V) The trigeminal is sensory to the face and forehfcad and motor to
the muscles of mastication.

(VII) The facial is motor to the muscles of facial expression. It
runs with the auditory in the internal auditory meatus and then
passes close to the mastoid air cells and the middle ear. •

(VIII) The auditory is sensory and is concerned with hearing and
balance.

(IX) The glossopharyngeal is a mixed nerve supplying the pharynx
and the tongue.

(X) The vagus is mixed and supplies most of the alimentary canal,
the respiratory tract and the heart.

(XI) and (XII) These are both motor. The former is the spinal
accessory and supplies the trapezius and sternomastoid muscles, and
the latter, the hypoglossal, supplies the muscles of the tongue.

THE SPINAL CORD

«

The spinal cord lies in the spinal canal and extends for about 18
inches below the foramen magnum, ending at the level of the first
lumbar vertebra in the adult. It shows two enlargements, one in the
cervical region and the other between the ninth and twelfth thoracic
vertebrae, called the lumbar enlargement. From its lower end
opposite the first lumbar vertebra a fibrous strand, the fUum lerminale,
runs down to the second sacral vertebra. As the cord is so much
shorter than the spinal canal the lumbar, sacral and coccygeal
nerves run from the lumbar enlargement to the lumbar inter-
vertebral and sacral foramina, forming a leash of nerves accompany-
ing the filum terminale known as the cauda equina.

The spinal cord is composed of grey matter which, unlike that of
the brain, is placed deeply as an H-shaped column surrounding the
central canal. The four processes of the H are the two anterior and
two posterior horns and in front, behind and on either side of the grey
matter is the white matter which, like that of the brain, consists of
nerve-fibres.

The functions of the spinal cord are:

(1) To transmit afferent (sensory) impressions to the brain and
efferent (motor) impulses from the brain.

(2) To take part in a type of jactivity known as reflex action,

THE SPINAL NERVES

There are 31 pairs of spinal nerves comprising 8 cervical, 12
thoracic, 5 lumbar, 5 sacral and i coccygeal. Each leaves the cord

THE SPINAL CORD

247

Level of Junction
1-2 Lumbar Vert.

Dura (cut)

Posterior Root Ganglion

Dura (cut)

Level of Lumbosacral
Junction

Dura (cut)

Level of Junction of
2-3 Sacral Vert.

Fijr. 17.5 The lower end of the dura and arachnoid laid open
to expose the cauda equina.

THE NERVOUS SYSTEM

248

by an anterior and a posterior root which unite outside it to form
the trunk of the spinal nerve. Many of these nerves branch and

Posterior

colnfnns

Posterior horn
of grey matter

. Pyramidal
tracts

Central canal

Anterior horn
of grey matter

Anterior

column

Fig. 1 7.6 Transverse section of the spinal cord showing the grey matter and
the position of the tracts in the white matter.

unite to form plexuses from which nerves are distributed to various
parts of the body. The cervical plexus is made up by the first to
fourth cervical nerves, the brachial by the fifth cervical to first

thoracic, the lumbar by the first to fourth lumbar and the sacral
plexus by the fourth lumbar to fifth sacral nerves. The nerve to the
diaphragm, the phrenic, comes from the cervical plexus, the nerves

THE SPINAL CORD 249

to the arm comtf from the brachial and those to the legs come from
the lumbar and sacral plexuses.

THE MOTOR PATH (see Fig. 17.7)

The motor impulses originate in the cells of the precentral gyrus of
the cerebral cortex and travel down the upper and lower motor
neurons.

The upper motor neuron starts, therefore, in the grey matter of the
brain and continues down as the axon of the brain-cell in the white
matter. In the medulla oblongata the axon crosses to the opposite
side and then travels by the pyramidal tract in the lateral column of

Cerebral

cortex

Cerebellum

Posterior
- column

Lateral

column

-Spinal cord

Fig. 1 7.8 The sensory path.

the white matter of the spinal cord. It terminates in an anterior
horn cell of spinal grey matter.

The lower motor neuron begins in an anterior horn cell and con-
tinues as the axon of this cell passing through the anterior nerve
root to the main trunk of the spinal nerve and so reaches its destina-
tion, for example, a muscle.

R

2^0

THE NERVOUS SYSTEM

THE SENSORY PATH (see Fig. if.8)

The sensory impulses which travel in the cord are divided into
those of superficial sensation such as pain, temperature sense and
touch and those of deep sensation such as those from fhuscles and
joints. They travel in fibres which enter the spinal cord by the
posterior root and pass to the posterior horn of grey matter. iVom
here the fibres run upwards in bundles or tracts in the white matter
of the spinal cord crossing to the opposite side in the cord or lower
part of the medulla to end in the postcentral gyrus of the cerebral
cortex of the opposite side of the body from which they originated.
Some fibres carrying sensations which do not enter consciousness
end in the cerebellum.

REFLEX ACTION

A reflex is a motor response, such as the activity of a gland when
it secretes or a movement produced by a muscular contraction
resulting from a sensory stimulus. A reflex is usually involuntary and
for its production it requires:

Sensory nerve

endings m skin. Posterior root ganglion

fibres

Fig. 17.9 Diagram illustrating reflex action.

(1) A receptor (sensory) organ such as the nerve-endings in the
skin, etc., to receive the stimulus.

(2) A sensory or afferent fibre to transmit the impulse to the
spinal cord.

(3) Connector fibres between the anterior and posterior horns of
the grey matter of the spinal cord.

(4) A motor neuron running from the nerve-cells of the anterior

THE MENINGES

251

horn of the spiiM grey matter to the organ in which the activity is
going to occur.

Examples of reflex activity include coughing and sneezing as a
result of inhalation of particles of matter into the nose and larynx,
the knee jerk, and the contraction of the pupil when the eye is
exposed to light.

THE MENINGES

The brain and spinal cord are surrounded by membranes whose
main function is protective. These are the dura mater, the arachnoid
mater and the pia mater.

Subcutaneous tissue

Epicranial

aponeurosis

Loose areolar tissue
Pericranium

Arachnoid

granulations

Superior
sagittal sinus

Falx cerebi

Subarachnoid space

Fig. 17.10 Diagram of coronal section through the scalp and skull. The arachnoid
granulations are seen projecting into the superior sagittal sinus.

The dura mater is a tough fibrous membrane composed of two
layers. It lines the skull and dips between the two cerebral hemi-
spheres forming the falx and separates them from the cerebellum by

THE NERVOUS SYSTEM

252

the tentorium. The two layers are fused except at' the sites of the
venous sinuses of the brain (p. 136) which lie between them.

The arachnoid mater lines the dura mater and sends small projec-
tions into the venous sinuses known as the arachnoid villi and arachnoid
granulations through which the cerebrospinal fluid is retJrned to the
blood stream.

The pia mater is a very thin membrane which closely invests the
surface of the brain, dipping into the sulci and carrying blood
vessels to the cortex. Between the pia and the arachnoid mater is the
subarachnoid space which is filled with cerebrospinal fluid, it sur-
rounds the brain and spinal cord and extends down as far as the
second sacral vertebra.

THE CEREBROSPINAL FLUID

This fluid fills the ventricles and subarachnoid space. It is secreted
by the choroid plexuses of the ventricles and kaves the ventricular
system by passing into the subarachnoid space through the foramina
in the roof of the fourth ventricle. It is absorbed from the sub-
arachnoid space into the blood stream through the arachnoid villi
and arachnoid granulations which project into the venous sinuses.

The cerebrospinal fluid is similar to lymph, being a clear colour-
less slightly alkaline fluid containing protein, glucose and salts. It
acts as a protective cushion for the brain and spinal cord, it carries
nourishment from the blood to the brain and spinal cord and it
removes excreta from them.

THE AUTONOMIC NERVOUS SYSTEM

The autonomic nervous system consists of a series of nerves and
ganglia which control the involuntary functions of the body.
Whereas the central nervous system is principally concerned with
the reception of sensory impulses and the stimulation of voluntary
muscle, the autonomic nervous system is principally concerned with
the innervation of the secretory glands and the involuntary (un-
striped) muscle of the body such as that of the heart,* blood vessels
and uterus. This system is not under control of the will but it is
intimately connected with the thalamus, the part of the brain
associated with the emotions.

* Heart muscle is involuntary but, strictly, it should not be classified as
unstriped (Chapter 3).

THE CEREBROSPINAL FLUID

Cerebral hemisphere —

Lateral ventricle

Interventricular foramen
Third ventricle

Cerebral aqueduct —
Fourth ventricle -

Subarachnoid space -

Central canal of spinal
cord

Superior longitudinal sinus
Cerebral hemisphere

Lateral ventricle -
Third ventricle -

Cerebellum

Fourth ventricle—

Subarachnoid space —

Central canal of spinal
cord

ia)

Fig. 1 7. 1 1 The circulation of the cerebrospinal fluid (diagrammatic)
(a) seea from the side, (A) seen from the back.

254 the nervous system

The nerves and ganglia of this system are derived Yrom the central
nervous system and are grouped as follows:

(1) The sympathetic nervous system.

(2) The parasympathetic nervous system.

The sympathetic nervous system consists of a series of ganglia in the
neck, chest (the cardiac plexus) and abdomen (the solar plexus,
etc.) which are connected to the thoracic and upper lumbar portions
of the spinal cord. From the ganglia the sympathetic nerve-fibres
pass to all parts of the body. The function of this part of the autono-
mic system is similar in effect to the injection of adrenaline, and in-
deed the suprarenal medulla which secretes adrenaline develops from
the same embryological tissue. The sympathetic and parasympathetic
nervous systems are antagonistic to each other and stimulation of
the sympathetic results in acceleration of the heart, constriction of
the cutaneous and alimentary blood vessel Sj contraction of the
sphincters, relaxation of the bronchi and dilatation of the pupils of
the eyes.

The parasympathetic nervous system comprises tlie cranial part and the
sacral part. The former consists of fibres which are distributed to the
pupils of the eyes, the blood vessels and secretory glands of the head
and neck; and the vagus nerve which supplies many organs in the
neck, chest and abdomen. The sacral part of the parasympathetic
system is derived from the sacral segments of the spinal cord and is
distributed through its ganglia to the lower parts of the alimentary
canal, the genital organs, etc.

As the sympathetic and parasympathetic nervous systems are
opposed in their functions it follows that stimulation of the latter
results in slowing of the heart, contraction of the pupils, dilatation of
blood vessels and relaxation of sphincters.

Radiographic Appearances of the Central Nervous System

Among the radiographic methods which may be used for studies
of the central nervous system are the instillation of air into the
ventricular system (ventriculography and encephalography), the
injection of an opaque medium into the carotid and vertebral
arteries (cerebral arteriography) and the injection of another opaque
medium into the spinal subarachnoid space (myelography) .

Encephalography and ventriculography will demonstrate the
ventricles of the brain if the patient’s head is suitably positioned, as

THE NERVOUS SYSTEM

255

the air will tencj to collect in the uppermost parts of the cavities. In
the lateral projection the lateral ventricle of the uppermost side will
be shown and the anterior horns of both lateral ventricles will be
filled when the patient is supine.

Injections of air for encephalography and of the opaque medium
for myelography may be made by lumbar puncture, A suitable needle
is inserted between the laminae of the third and fourth lumbar
vertebrae and cerebrospinal fluid escapes when the subarachnoid
space has been reached. There is no fear of damage to the cord
because, of course, this terminates between the first and second
lumbar vertebrae.

Fig. 17.12 Radiograph of the skull, lateral projection, showing the lateral ventricle
of one side outlin^ by air.

In myelography the opaque medium is made to ascend and
descend the spinal subarachnoid space by tilting the table in the
appropriate direction. The medium will normally descend as far as
the second sacral vertebra because the subarachnoid space extends
down to this level.

Pathological Considerations

Damage to the motor tracts of the brain is often caused by

THE NERVOUS SYSTEM

256

haemorrhage or thrombosis resulting from arterial cfisease. Paralysis
of one-half of the body, called hemiplegia^ may follow. Pressure on
the spinal cord by fracture-dislocations of the spine, prolapsed inter-
vertebral discs or spinal tumours may cause paralysis of the lower
limbs, a condition known as paraplegia. If all four limbs are para-
lysed the patient is quadriplegic. Infantile paralysis (anterior
poliomyelitis) often destroys some of the anterior horn cells of the
spinal cord and produces what is known as a flaccid paralysis (in
contradistinction to a spastic paralysis which follows damage to the
upper motor neuron).

Tumours of the brain may cause a rise in intracranial pressure
and this may result in thinning or destruction of the posterior
clinoid processes and dorsum sellae, enlargement of the pituitary
fossa and, in children, separation of the cranial sutures.

Tumours of the auditory canal called acoustic neuromas may
occur and they may produce expansion of the auditory canal which
can be demonstrated radiologically.

The circulation of the cerebrospinal fluid may be impeded by a
block in the cerebral aqueduct (e.g. a tumour) or inflammatory
disease of the meninges causing adhesions in the subarachnoid space
or blocking the foramina in the roof of the fourth ventricle. Under
these circumstances the continued formation of the fluid results in
distension of the ventricles and pressure atrophy of the brain. This
condition is known as hydrocephalus (water on the brain). It is now
possible to relieve the condition by surgical procedures.

i8

The Special Senses

Sensations may be divided into those arising within the body such
as thirst, hunger, muscle sense, etc., and those, called the special
senses, arising from external stimuli such as sight, hearing, taste,
smell and touch.

SIGHT

T'hc organ of sight is the eye and it has various accessory structures
which include the eyebrows, the eyelids, the conjunctiva, the

Sclerotic Coat Choroid Coat

Fig. i8. 1 Section through the eyeball.

lacrymal apparatus (all protective in function), and the muscles
which arc responsible for the synchronized movements of the eyes.

The eyeball is a mechanism for modifying light waves so that they
will stimulate the nerve endings in the retina. It consists of three
coats which enclose a number of transparent structures. The outer
coat or sclera forms the white of the eye and is a tough fibrous layer
which gives the eye its shape and is transparent anteriorly where it is
called the cornea. The middle coat or choroid is vascular and pig-
mented and is continuous with the iris. The innermost coat, the

257

THE SPECIAL SENSES

258

retina^ is continuous with the optic nerve and is composed of nerve
endings which are sensitive only to light.

The eyeball is divided into an anterior and a posterior chamber. The
anterior chamber contains the transparent aqueous humour and
is separated from the posterior chamber by the lens. The incoming
light rays are focused by the lens, the curvature of which can be
varied by contraction of the muscles of the ciliary body (accom-
modation). The posterior chamber is occupied by the transparent
vitreous humour. I’he amount of light entering the eye is controlled by

Eye

Right Eye

Note that the nerves
from the inner half cf
both eyes cross here
(Optic chiasma)

Injury here will cause
loss 1 4 sight of the
right eye, but the left
eye will still see both
hous and tree

Left Side
Injury here will cause
loss of sight of the
house

Right Side

Injury here will cause
loss of sight of the
tree

Fig. 18.2 Diagram of the visual paths.

the iris, a pigmented structure composed principally of smooth
muscle, which dilates in poor light and contracts in bright light.

The retina consists of nerve-cells and is developmentally part of
the brain. The nerve-fibres are greatly modified and are called rods
and cones. The cones are used for vision in good lighting conditions
whereas the rods are used for ‘night vision’, they do not function in

HEARING

259

bright light as diey require the presence of a pigment called visual
purple which is bleached by exposure to light. Exclusion of light from
the eyes for 15-20 minutes or the wearing of red goggles results in
the recovery of visual purple; this is called dark adaptation.

That part of the retina to which the optic nerve is attached is
devoid of rods and cones and is called the blind spot. Lateral to this
and in the centre of the retina directly behind the pupil is the most
sensitive part; it is called the macula and is rich in cones but has no
rods, so it is not used in ‘night vision’.

The nerve impulses resulting from the stimulation of the retina by
light are transmitted by the optic nerves to the optic chiasma where
fibres from the inner half of each retina cross to the opposite side so
that when they are distributed to the occipital cortex impulses from
the right half of each retina will be distributed to the right side of the
brain and those from the left side will go to the left side of the brain.

The conjunctiva is a very thin mucous membrane which lines the
eyelids and covers the cornea.

The lacrymal apparatus consists, on each side, of the lacrymal glandy
a pair of lacrymal ducts and, leading from the inner part of each orbit
to the inferior meatus of each side of the nose, the nasolacrymal ducts.
The glands lie above the outer parts of the eyes and the tears which
they produce pass via the upper and lower lacrymal ducts to the
nasolacrymal ducts and thus reach the nose.

HEARING

The ear consists ofithc external,, middle and internal ears and in

26 o

THE SPECIAL SENSES

addition to being the organ of hearing it is concerned with the
maintenance of the body’s equilibrium.

The external ear consists of the pinna or auricle and the external
auditory meatus^ a bony and cartilaginous canal which leads to the
middle ear but is separated from it by the drum or tympanic membrane.
The bony part of the meatus lies between the petrous temporal bone
above and the tympanic part of the temporal bone below.

The middle ear is a narrow cavity in the petrous part of the tem-
poral bone and contains three tiny bones or ossicles called the
malleus (hammer), the incus (anvil) and the stapes (stirrup). The
lateral wall is formed by the tympanic membrane and the medial
wall is bony but has two membrane-covered apertures which
separate it from the vestibule above and the cochlea below, called

Fig. 18.4 The structure of the ear.

the fenestra ovalis and the fenestra rotunda respectively. The mastoid air
cells and mastoid antrum communicate with the middle ear through
its posterior wall.

The auditory [Eustachian or pharyngotympanic) tube which connects
the middle ear to the pHarynx (p. 145) opens into the anterior wall
of the middle ear cavity and en^ibles the pressure in this cavity to be
adjusted to that of the atmosphere because, although the walls of the
tube are normally in contact with each other, the movements of
swallowing and yawning separate them. Sudden ascent or descent,
as in an elevator in a high building, alter the pressure which the
atmosphere is exerting on the ear-drum and swallowing is often
required to adjust the pressure in the middle ear and relieve the

HEARING

201

discomfort felt ifi the drum when the pressures on either side of it
are different.

The internal ear or labyrinth is the part of the ear concerned with
Iji^lance as well as hearing and consists of a number of communi-
^ eating membranous structures, namely, the vestibule, the cochlea
and the semicircular canals, containing fluid called endolymph. They
lie in the bony labyrinth which is formed by similarly shaped cavities

Temporal m.

lot aud. meatue

Int. Jugular vein i TvC /

>- ■>1 ; V

Tragus of ear

roroMd gland

Sterno-maatold

Fig. 18.5 Coronal section through the external and internal auditory meatus

(diagrammatic).

in the petrous parts of the temporal bone; fluid called perilymph
separates the bony from the membranous parts.

The cochlea^ the organ of hearing, is a coiled structure projecting
forwards from the vestibule and in shape is somewhat like a snail. It
contains layers of specialized cells called the organ of Corti which
come into intimate contact with the auditory part of the eighth
(auditory) nerve (p. 246) where the sound vibrations are converted
into nerve impulses.^

262 THE SPECIAL SENSES

The Mechanism of Hearing *

The cavity of the middle ear is crossed by the ossicles, the malleus
being connected to the tympanic membrane, the stapes to the
membrane covering the fenestra ovalis and the incus iintervenin'*^
between them. Vibrations of the tympanic membrane produced by
sound waves which have entered the external auditory meatus are
transmitted by movement of the ossicles across the middle ear to
the membrane covering the fenestra ovalis, from which they are
transferred to the perilymph and endolymph. The cochlea is
stimulated by the vibratory movement of the endolymph and the
organ of Corti converts the stimuli into impulses which the auditory
nerve conducts to the brain.

The semicircular canals are the organs which provide one of the
means by which the position of the body in space can be appreciated.
It will be recalled that sensory impulses from muscles and joints
provide another mechanism for the orientation of the body. The
canals are called the superior, the posterior and the lateral, and
they are so placed that they are at right angles to each other. They
communicate individually with the vestibule and contain endolymph
and a special sensory mechanism which comes into intimate contact
with the vestibular part of the auditory nerve. The sensory mechan-
ism is stimulated by movement of the endolymph resulting from
alteration in the position of the head and this information is carried

CUTANEOUS SENSATION 263

to the brain wlfere the auditory nerve has connections with both
thd' cerebrum and the cerebellum.

Taste and Smell

These are closely related sensations dependent upon chemical
stimulation. The special end-organs of taste are called taste buds
and these are found in groups on the dorsum, sides and tip of the
tongue and in the mucous membrane of the palate and pharynx.

Epiglottis

Vallecula

Fig. iy.7 The parts of the tongue in which the
variou.5 sensations of taste are appreciated.

They are sensitive to the four primary taste sensations, sweet, bitter,
sour and salt, and sensitivity to each is localized to a particular part
of the tongue. The aroma or flavour of food is appreciated by the
sense of smell and this close association of taste and smell is common
knowledge, much of the sense of taste being lost in the presence of a
cold in the nose.

The sense of smell is stimulated by inhaled gases or particles of
soluble matter and is readily fatigued. The end-organs of the olfac-
tory nerve lie in the mucous membrane of the upper part of the
nasal cavity.

Cutaneous Sensations

The skin possesses four different types of end-organ which are
sensitive to heat, cold, pain and touch respectively. These are

THE SPECIAL SENSES

264

scattered over the surface of the body but are mor^ concentrated in
some areas than others. The acuteness of these sensations depends on
the concentration of the particular nerve endings, for instance, f^he
finger tips are rich in touch end-organs and they are particulat^jv
sensitive in this respect. ^

19

urface Anatomy and Surface Markings

THE HEAD AND NECK

The nasion is the depression at the root of the nose and it lies just
below the glabella which is the slight elevation on the frontal bone
between the two eyebrows. Two ridges, the superciliary arches^ run
laterally from the glabella, and the frontal air sinuses lie deep to

Fig. 19.1 Lateral view of head showing various landmarks and the anterior
and posterior triangles of the neck.

them. The inion or external occipital protuberance is a localized
prominence on the occiput at the junction of the back of the head
with the back of the neck. Immediately behind the ear is the mastoid
process and in front of the external auditory meatus the zygomatic arch
runs forwards towards the orbit.

The inner and outc( canthi (sing, canthus) are the junctions of the
s 265

256

SURFACE ANATOMY

eyelids. The outer canthus can be joined to the External auditory
meatus by the orbitomeatal line. Another line, the Frankfurt line, is also
used in radiographic positioning; it joins the lower orbital margir^ to
the upper margin of the external auditory meatus. The inierpupilh^v
line is the line passing through the centres of the pupils'of the eyes.

The sella turcica (pituitary fossa) lies i inch (2.5 centimetres) in
front of and the same distance above the external auditory meatus.

The medial border of the sternomastoid muscle can be felt running
from the mastoid process to the manubrium of the sternum and this
serves as a surface marking for the position of the common, internal
and external carotid arteries. This muscle also divides the neck into

L. subclavian a.

R. innomi-
nate V.

Sup. vena
cava

Ascending

aorta

K. siipra-
leiial

K. kidney

Pancreas

Clavicle

L. innomi-
nate V.

Pulmonary a.
Axillary a.

Mitral valve

'J'ricuspid

valve

Brachial a.

Abdominal

aorta

Inf. vena cava
Ulnar a.

Fig. 19.2 The heart and great vessels. Duodenum, pancreas, kidneys, etc.

the anterior and posterior triangles. In the former are the larynx,
the trachea and the thyroid gland.

At the junction of the neck and back the prominent spinous process
which can be felt easily is usually that of the seventh cervical
vertebra and it is often called the vertebra prominens.

THE LARYNX

This region is easily palpated and, if the finger is run down the
front of the neck from the chin, the upper border of the thyroid
cartilage is felt immediately below the hyoid bone at the level of the
middle of the third cervical vertebra. The anterior arch of the

SURFACE ANATOMY

cricoid cartilage? is palpable immediately below the thyroid cartilage
at the level of the lower border of the sixth cervical vertebra.

THYROID GLAND

This lies on the anterior and lateral aspect of the upper six rings of
the trachea. The isthmus lying about \ inch (i centimetre) below
the cricoid cartilage and the lower poles of the lateral lobes reaching
about 1 inch (2.5 centimetres) below this.

THE THORAX

The sternum is subcutaneous and can be palpated throughout its
length. Its upper margin is on a level with the lower part of the body
of the second thoracic vertebra. The second costal cartilage can be
felt at the level of the sternal angle which forms an obvious prominence
anteriorly and corresponds to the interspace between the fourth and
fifth thoracic vertebrae posteriorly. In the female the breast occupies
approximately from the second to the sixth ribs and extends from
the lateral margin of the sternum to the anterior axillary fold. The
nipple lies at about the level of the fourth intercostal space.

Trapo/ius ni. ^uprasternal notch Supraclavicular fossa

Sternal
angle

Deltoid ra.
Biceps m. #
Linca alba

Med. basilic

V.

Fig. 19.3 The lines of pleural reflection.

The heart lies behind the sternum and extends in the recumbent
position from the sternal angle above to about inches (4 centi-
metres) beyond the xiphisternal joint below. The right border lies
about i \ inches (4 centimetres) to the right of the midline (i.e.about
\ inch (i centimetre) to the right of the sternum). The apex is

268

SURFACE ANATOMY

situated about 3^ inches (9 centimetres) to the left of the midline,
behind the fifth intercostal space and the left border extends from
this point to the left side of the sternal angle. In the erect posititm
the heart moves down nearly an inch in relation to the sternum.
arch of the aorta lies behind the lower half of the manuBrium of the ‘
sternum.

The apex of the lung and upper limit of the pleura reach to about 1 1
inches (4.5 centimetres) above the middle of the clavicle but in-
feriorly the lung does not reach the lower limit of the pleura owing
to the presence of the costodiaphragmatic recess. The lower limit of the
pleura is represented approximately by a line with a slight upward
inclination drawn round each side of the body at the level of
the twelfth thoracic spinous process. This line should pass through
the eighth rib in the nipple line, the tenth in the midaxillary line, the
eleventh in the midscapular line and the twelfth at the lateral margin
of the sacrospinalis muscle. I’he lower border of the lung is approxim-
ately two intercostal spaces above that of the pleura.

The bifurcation of the trachea, that is the division of the trachea into
the two main bronchi, is at the level of the sternal angle.

thp: abdomen

The regions of the abdomen and the lines which divide them have
already been described in Chapter 13.

Bodily Types

It is obvious that human beings vary between the extremes of
those with long narrow trunks and those with short broad ones ; the
disposition of the abdominal organs depends partly on the body type
of the individual. We may thus recognize the slender trunk type
(also called asthenic or hyposthenic) and the broad trunk type (or
hypersthenic).

The slender trunk type has a narrow subcostal angle, a long lumbar
spine, abdominal organs which arc low lying and a heart that tends
to be long and narrow.

The broad trunk type has a wide subcostal angle and a short lumbar
region. The abdominal organs tend to be high and the heart is more
transversely placed than in the slender type.

Between these extremes is the individual of average build (or
orthos thenic).

SURFACE ANATOMY

i

Many factors^ influence the position of the viscera in the individual
subject and amongst these are:

^(i) Posture.

(2) Respiratory movement.

(3) Muscle tone of the abdominal wall and of the internal organs.

(4) The degree of fullness of hollow viscera.

Fig. 19.4 13 iagram illuslrating (1) tht* broad trunk type of individual (hypersthenic)
and (2) the slender trunk type of individual (hyposthenic).

Posture. When an individual moves from recumbency to the up-
right position many abdominal viscera descend about 2 inches (5
centimetres).

Respiratory movement. If an individual inspires deeply using his
diaphragm many abdominal viscera will descend 2 or 3 inches (5-7
centimetres) .

The degree of fullness of hollow viscera. The most obvious example of
this factor influencing the position of internal organs is the dis-
placement which occurs in the presence of a pregnant uterus.

The transpyloric plane lies approximately midway between the
umbilicus and the joint between the xiphoid and the body of the
sternum and it forms the boundary between the upper two rows of

SURFACE ANATOMY

the regions of the abdomen. This plane indicates*" the position of
many important organs and in the expiratory phase with the subject
recumbent the following structures lie at this level:

(1) The pylorus.

(2) The duodenojejunal flexure.

(3) The upper border of the pancreas.

(4) The hila of the kidneys; the right is an inch or so lower than
the left and the centre of each hilum is about 2 inches from the
midlines.

(5) The tip of the ninth costal cartilage.

(6) The fundus of the gall-bladder.

(7) The upper part of the body of the first lumbar vertebra

(8) I’he lower end of the spinal cord.

SURFACE ANATOMY

i>l

xiphisternal joint from a point 3 inches (7.5 centimetres) to the left
of^e mi’dline to the right axilla; the lower border may be drawn by
C(mnecting the left extremity of this line to the lowest part of the
rjght costal margin laterally and the right bolder will coincide with the
chest wall laterally.

The Spleen

The long axis of the spleen corresponds with the posterior part of
the left tenth rib reaching from the mid-axillary line anteriorly to
I ^ inches (4 centimetres) from the midline posteriorly.

The Pancreas

The pancreas runs across the posterior abdominal wall from its
head which lies in the curve of the duodenum, on the right of the
first and second lumbar vertebrae, to its tail which lies in the left
hypochondrium where it ends near the hilum of the spleen. The
pancreas lies obliquely its tail being at a higher level than its head
but the upper border of its body is approximately on the level of the
transpyloric plane, fhe lower border of the body is about inches
(3 4 centimetres) below the upper and the two hol ders meet at the
termination of the tail of the gland.

The Kidneys

In a subject lying supine the hila of the kidneys, at the end of
expiration, arc approximately at the level of the transpyloric plane
which crosses the middle of the costal margin; the right kidney is
usually about i inch (2.5 centimetres) below the left and both hila arc
about 2 inches (5.0 centimetres) from the midline. Bearing in mind
that the kidneys arcabout4i inches (12 centimetres) longand 2 inches
(5.0 centimetres) wide and that the hila arc approximately midway
between the upper and lower ends their positions can thus be
mapped out on the anterior abdominal wall. In relation to the spine
the kidneys extend from the twelfth thoracic to the third lumbar
vertebra and the hila arc opposite the first lumbar vertebra.

The Ureters

The ureter of each side runs from the hilum of the kidney (on the
transpyloric plane 2 inches (5 centimetres) from the midline) down-
wards and medially to the level of the pubic tubercle.

The Urinary Bladder

The empty bladder in the adult lies behind the pubic bones and

SURFACE ANATOMY

the symphysis but as it fills it rises into the hypog&stric region. In
childhood the bladder is principally an abdominal organ because >^0
pelvic cavity is relatively much less spacious than in the adult.

The Uterus

The non-pregnant uterus lies behind and above the bladder, that
is, low in the hypogastrium.

THE UPPER LIMB

The clavicle is subcutaneous throughout its course and below its
outer end is the coracoid process. Lateral to this is the head of the
humerus and above this the acromion can be felt. The axilla is the angle
between the arm and the chest and the cubital fossa is in front of the
elbow. On the back of the elbow the medial and lateral epicondyles
and the olecranon process form easily palpable prominences. The line
of the elbow joint is f inch (2 centimetres) below that which joins the
two epicondyles. l^he radial and ulnar styloid processes can be palpated
on either side of the lower end of the forearm and the position of the
wrist joint corresponds to a line, convex upwards, joining these
processes. The scaphoid is immediately distal to the radial styloid
process.

THE LOWER LIMB

The hip joint lies ^ inch (i centimetre) below the middle third of
the inguinal ligament and the latter corresponds in position to the fold
of the groin. The greater trochanter of the femur is the most prominent
bony structure palpable on the lateral side of the thigh. At the back
of the knee is the popliteal fossa and anteriorly about i J inches (4
centimetres) below the lower border of the patella when the knee is
extended is the tibial tuberosity. About \ inch (i centimetre) below
the lower border of the patella in the same position is the line of the
knee joint. The medial surface of the tibia is subcutaneous and at its
lower end the medial malleolus forms a prominence. The lower end of
the fibula, the lateral malleolus, lies on a plane posterior to the medial
malleolus and reaches to a lower level. In front of the base of the
lateral malleolus the lower end of the tibia can be felt and the ankle
joint will lie immediately below this.

Abdomen,

Boundaries of, 181
contents of, 181

radiographic appearance of, 182
regions of, 182
Abducent nerve, 245
Abduction, 35
Absorption of food, 191
Acetabulum, 90
Achilles tendon, 1 18
Acromegaly, 232
Acromion, 75
Adaptation, visual, 259
Adduction, 351
Adenoids, 162

Adrenal glands — see suprarenal glands

Adrenaline, 237

Afferent lymph vessel, 160

Alimentary canal, 169

Alveoli of lungs, 151

Amoeba, 6

Amylase, 189

Anabolism, 5

Anal canal, 192

Angle of sternum, 69

Ankle joint, 101

region, radiographic appearance of,
103

Anti-anaemic factor, 141, 187, 201
Antrum, maxillary- -see maxillary sinus
tympanic, 39
Aorta, abdominal, 130
arch of, 129
ascending, 129

bifurcation of abdominal, 130
descending, 129

thoracic, surface markings of, 268
Appendix, vermiform, 191
Aqueduct, cerebral, 244
Aqueous humour, 258
Arachnoid mater, 252
Areola (of breast), 226
Arteries, structure of, 119
Arteriole, 119
Artery, axillary, 133
basilar, 132
brachial, 133
bronchial, 129
carotid, common, 131
external, 131
internal, 132
coronary, 123, 129

femoral, 135
hepatic, 200
iliac, common, 131
external, 131
internal, 131
innominate, 129
middle meningeal, 44, 131
popliteal, 135
pulmonary, 129
radial, 133
renal, 131
subclavian, 129
ulnar, 133
vertebral, 132
Articulations — sec joints
Arytenoid cartilages, 145
Asepsis, 27

Atrium (of heart), 122
Auditory nerve, 39, 246
tube, 145, 260

Auricle (of external ear), 260
Auricle (of heart), 124
Autonomic nervous system, 252
Axilla, 112, 272

lymph nodes of, 161
Axis, 62
Axon, 12
A^ygos vein, 1 30

Bacteria, 25
Basal metabolism, 208
Biceps muscle, of arm, 1 13
Bicipital groove, 75
tuberosity of radius, 78
Bile, ducts, 201
function of, 203
pigments, 201
salts, 201
secretion of, 200
Biological effect of radiation, 23
Bladder, gall-, 201
urinary, 212
Blind spot, 259
Blood, 139
cells, 140

circulation of, 125
clotting of, 142
composition of, 140
functions of, 139
plasma, 140
platelets, 142
Bodily types, 268

273

Bone, development of, 19
factors controlling, 22
structure, of, 1 8
Bones, long, 30
sesamoid, 30
short, 30

terms used in describing, 30
Brain, parts of, 242
Breast, 225

lymph drainage of, 164
Broad ligaments of uterus, 223
Bronchus, ISO
Bundle of His, 124

Caecum, 191
Calcaneum, 95
Callus, 36
Caloric, 208
Calyx, 209

Canal, adductor, 115, 135
central of spinal cord, 244, 246
Haversian, 18
mandibular, 46
optic, 42
semicircular, 262
Canthus of eye, 265
Capillary,
bile, 201
blood, 120
lymph, 158
Capitate bone, 80
Cardia of stomach, 186
Carpus, bones of, 80
radiographic appearance of, 89
Carrying angle of elbow, 77
Cartilage, 16
articular, 17
arytenoid, 145
costal, 71
cricoid, 148
fibro-, 17
hyaline, 17

semilunar, see meniscus
thyroid, 148
triangular (of wrist), 87
triradiate, 91
Catabolism, 5
Cauda equina, 246
Cavity, glenoid, 75
nasal, 48
Cell, 4

Cerebellum, 244
Cerebrospinal fluid, 252
Cerebrum, 242
Chamber (of eye),
anterior, 258
posterior, 258
Choroid (of eye), 257
plexus, 244
Chromosome, 5
Chyle. 159
Chyme, 189
Cilia, 9

Circle of Willis. 132
Circular folds (of small intestine), 188
Circulation of the blood, 125
Circumduction, 35

Cisterna Chyli, 158 i
Clavicle, 74
Climacteric, 226
Clinoid processes,
anterior, 42
posterior, 41
Clitoris, 225
Coccyx, 63
Cochlea, 261
Colon, 192
Colostrum, 227
Concha, 48
Condyle, 30
of femur, 93
of mandible, 46
of occipital bone, 41
Cones (of eye), 258
Conjugate,
transverse, 92
true, 92

Conjunctiva, 259
Connective tissue, 1 1
Cornea, 257

Coronoid process of mandible, 46
ulna, 79 ♦

Corpus cavernosum, 221
luteum, 222, 239
spongiosum, 221
Corpuscle, see blood cells
Cranium, 37

Cribriform plate (of ethmoidal bone), 42
Crus (of diaphragm), 1 10
Cubital fossa, 272
Cuboid, 96

Cuneiform bones of foot, 96

Defaecation, 198
Deglutition, 197
Dendron, 12
Dentine, 174
Dermis, 13
Diaphragm, 1 10
Diaphysis, 21
Diastole, 124
Diet, 208
Digestion, 5
in mouth, 178
in small intestine, 189
in stomach, 187
summary of, 207

Digestive system - see alimentary system
Disc, intervertebral, 64
Distal, I

Douglas, pouch of, 186
Duct, bile, 201
cystic, 201
ejaculatory, 220
hepatic, 201
lacrymal (tear), 259
lactiferous, 225
nasolacrymal, 259
pancreatic, 204
right lymph, 159
seminal, 220
Stenspn’s, 177
thors^cic 158
Wharton’s 177

INDEX

I ''

Ductless glands, 230
Duod^ffllm,' 187
Diy^ mater, 251

E; Y, 260
ectoderm, 8

Efferent lymph vessel, 160
Elastic tissue, 1 1
Elbow joint, 85

region, radiographic appearances of, 85
Enamel, 174
Endocardium, 123
Endocrine system, 230
Endoderm, 8
Endolymph, 261
Endometrium, 223
Energy requirements, 208
Enzyme, 5
Epicondyle, 30
of humerus, 75
Epidermis, 13
Epididymis, 219
Epiglottis, 145
Epiphysis, 21
Epithelium, types of, 9
Ethmoidal bone, 42

Eustachian tube, see tube, auditory, 145

Eversion, 102

Excretion, 5

Extension, 34

Eye, 257

Fabella, 100
Facet, 30
Facial nerve, 246
Faeces, 193

Fallopian tube, sec uterine tube
Falx, 251
Fascia, deep, 107
superficial, 107
Fauces, 169, 179
Femur, 92
Fenestra oval is, 260
rotunda, 260
Fertilization, 6
Fibula, 95

Filum terminale, 246
Fimbria, 225
Flexion, 35

Fontanelle, anterior, 45
posterior, 45
Food, 207
Foot, bones of, 95
joints of, 102

radiographic appearances of, 105
Foramen, 30
intervertebral, 58
magnum, 40, 44
obturator, 91
optic, 41

ovale (of skull), 44
spinosum, 44
transversarium, 61
vertebral, see f. transversarium
Formula, dental, 174
Fornix (of vagina). 225

Fossa,

anterior cranial, 43
coronoid (of humerus), 77
cubital, 272

infraspinous (of scapula). 75
middle cranial, 44
olecranon (of humerus), 77
piriform, see pyriform fossa
popliteal, 272
posterior cranial, 44
pyriform, 179
subscapular, 75
supraspinous, 75
Fourchette, 225
Fracture, 36
Frankfurt line, 265
Frontal bone, 38
Frontal sinus, 49
Fundus of stomach, 186

Gall bladder, 201
Gastric juice, 187
Gene, 6

Genital tract, female, 221
Gemto-urinary tract, male, 218
Germ layers, the three, 8
Girdle, pelvic, 90
Glabella, 265
Gland, Bartholin’s, 225
ductless, 10
lacrymal, 259

lymphatic, see lymph node

parathyroid, 235

parotid, 175

pineal, see pineal body

pituitary, 230

prostate, 221

salivary, 175

sebaceous, 15

sex, 239

sublingual, 177

submandibular (submaxillary), 177
suprarenal, 236
sweat, 15
thymus, 235
thyroid, 233
Glands, 10
Gians penis, 221
Glenoid cavity, 75
labrum, 81
Glomerulus, 212
Glossopharyngeal nerve, 246
Glucose, 178, 191, 201, 207, 238
Glycogen, 201, 238
Goitre, 234

Graafian follicle, 222, 239
Grey matter of brain, 241
of spinal cord, 246
Groove, bicipital (of humerus), 75

Habitus, see bodily types
Haemoglobin, 140
Hair follicle, 15
Hamate bone, 80
Haversian canal, 18
Healing of fractures, 36
Hearing, mechanism of, 262

INDEX

'276

Heart, 121

surface marking of, 267
radiographic appearances of, 12S
Heat production, 201
loss, 16

Hemisphere, cerebral, 242
Hepatic artery, 128
ducts, 201

flexure of colon, 192
veins, 138
Hip joint, 97
region, radiographic appearance of, 97
His, bundle of, 124
Hormone, 230
Humerus, 75

Hunter’s, canal, see canal, adductor
Hydrochloric acid, 187
Hymen, 225
Hyoid. 52

Hypochondriac region, 183
Hypoglossal nerve, 246
Hypothenar eminence, 155

lleocaecul junction. 191
valve, 191
Jleum, 188
Iliac region, 183
Ilium, 90
Incus, 260
Infection, 27
Inferior vena cava, 138
Inguinal canal, 1 10
ligament, 110
lymph nodes, 162
Tnion, 265

Innominate artery, 129
bone, 90
vein, 137
Insulin, 238

Intercondylar notch (of femur), 93
Internal carotid artery, 131
ear, 261

respiration, 153
secretions — see hormones.
Intervertebral disc, 64
foramen, 58
Intestine, large, 191
small, 187

Intrinsic factor — see anti-anaemic factor
Inversion, 102
Involuntary muscle, 1 1

nervous system — see autonomic ner-
vous system
Iris, 257
Ischium, 90

Islets of Langerhans, 238

Jaw, lower, 46
upper, 46
Jejunum, 188

Joint, acromioclavicular, 80
ankle, 101
elbow, 85
hip, 97

intervertebral, 64
knee, 98

radio-ulnar, 87
sacro-iliac, 92
shoulder, 80
sternoclavicular, 80
temporomandibular, 46
tibiofibular, 101
wrist, 87
Joints, 32

Jugular vein, internal, 136

Kidneys, 209
surface anatomy of, 271
radiographic appearances of, 215

Labia majora, 225
minora, 225
Labrum, acetabular, 97
glenoid, 81
Labyrinth, bony, 261
Lacrymal apparatus, 259
duct, 259
gland, 259
Lactation, 227
Lacteal, 159, 191
Lamina dura, 174
Lamina (of vertebra), 58
Langerhans, islets of, 238
Larynx, 145

surface anatomy of, 266
Lens (of eye), 258
Leucocyte, 141

Ligament, annular (of radius), 85
broad (of uterus), 223
coracoclavicular, 74
cruciate, 100
glenoid (labrum), 81
inguinal, 110
nuchae, 65

round (of uterus), 223
stylohyoid, 52
teres (of hip), 97
trapezoid, 74

Ligaments of vertebral column, 65
Line, Frankfurt, 265
interpupillary, 266
orbitomeatal, 266
Lipase, 189
Liver, 199

surface markings of, 270
Lunate bone (of carpus), 80
Lungs, 151

lymph drainage of, 165
surface marking of, 268
Lymph. 158
drainage, of:
breast, 164
lung, 165
ovary, 165
testis, 165
thyroid, 164
tongue, 163
tonsil, 163
uterus, 165

Lymph duct, right, 159
node,, 160

Lymphatic system. 158
Lymphocyte, 142

Macula, 259 ^

Malar 45
MaWeolus, lateral, 95
^ledial, 95 ■

MMIeus, 260
Mandible, 46
Mandibular joint, 46
Manubrium (of sternum), 69
Marrow, red, 167
yellow, 167
Mastoid antrum, 39
process, 39
Maxilla, 46
Maxillary sinus, 49
Meatus, external auditory, 39
of nose, 48
internal auditory, 39
Mediastinum, 120
Medulla oblongata, 243
Membrane, interosseous, of forearm, 87
interosseous, of leg, lOI
mucous, 12
tympanic, 260
Meninges, 251

Meniscus (of knee joint), 100
Menopause, 226
Menstruation, 226
Mesentery, 184
Mesocolon, pelvic, 192
transverse, 192
Mesoderm, 8
Metabolism, 5
basal, 208

Metacarpal bones, 80
Metaphysis, 22
Metatarsal bones, 97
Micturition, 215
Middle ear, 260
Mitosis, 5
Mitral valve, 122
Moiis veneris, 225
Motor cortex, 243
Mouth, 169

Movements of the alimentary canal, 197
Muscle, involuntary, 1 1
voluntary, 1 1

Muscles, adductor group (thigh), 118
biceps of arm, 1 13
brachialis, 113
deltoid, 1 12

hamstring group (of thigh), 117
iliacus, 1 16
latissimus dorsi, 109
pectoral is major, 1 12
psoas, 1 1 5

quadriceps femoris, 116
rectus abdominis, 110
sartorius, 1 1 5
sternomastoid, 108
subscapularis, 112
trapezius, 108
triceps brachi, 1 13
Myocardium, 123
Myxoedema, 234

J^ails, 15

Wares, anterior, 48

posterior, 48
Nasal cavity, 48
sinus, 49
Nasion, 265
Nasopharynx, 145
Navicular bone (of foot), 96
Neck, anatomical (of humerus), 75
radiographic appearances of soft tissues
of the, 179

surgical (of humerus), 75
triangles of, 109
Neoplasm, 28
Nerves, cranial, 245
spinal, 246
Nervous tissue, 1 1
Neurocentral joints, 65
Neuron, 12
motor, upper, 249
lower, 249
Nipple, 226

Node atrioventricular, 124
lymph, 159
Nose, 48
Nutrition, 206

Obturator foramen, 91
Occipital bone, 40
Occulomotor nerve, 245
Odontoid process, 59
Oesophagus, 179
Oestrogen, 239
Olecranon, 79

Olecranon fossa of humerus, 79
Olfactory nerve, 245
Omentum, 185
Optic canal, 42
foramen, 41
nerve, 245, 259
Orbit, 47

Organ of Corti, 262
Oropharynx, 179
Os tngonum, 96
Ossicles of ear, 260
Ossiheation of ankle region, 105
carpus, 89
elbow region, 87
hip region, 98
knee region, 101
shoulder region, 84
vertebral column, 69
Osteoblasts, 18
Osteoclasts, 21
Ovary, 221
Ovulation, 226
Ovum, 7, 222

Palate, hard, 169
soft, 169
Pancreas, 204
surface anatomy of, 271
Pancreatic juice, 189
Papillary muscles of heart valves, 1 24
Parasympathetic nervous system, 252
Parathormone, 235
Parathyroid gland, 235
Parietal bone, 38
pericardium, 123

Parietal peritoneum, 184
pleura, 153

Parotid salivary gland, 175
Patella, 95

Pectoralis major, 1 1 2
Pedicles of vertebrae, 58
Pelvic cavity, 91
colon, 192
girdle, 90
peritoneum, 185
Pelvis of kidney (ureter), 212
Pelvis, sexual characteristics of, 92
Penis, 221
Pepsin, 187
Pericardium, 1 23 p
Perilymph, 262
Perineum, 225
Perineal body, 225
Periodontal membrane, 170
Periosteum, 19
Peristalsis, 197
Peritoneum, 184

Petrous portion of temporal bone, 39
Peyer’s patches, 163 189
Phagocytosis, 26, 141
Phalanges of hand, 80
Phalanges of feet, 97
Pharyngotympamc tube, see tube, audi-
tory

Pharynx, 145, 178
Phrenic nerve, 1 1 1
Pia mater, 252
Pineal body, 240
Pinna (of ear), 260
Piriform fossa, see pyriform fossa
Pisiform bone, 80
Pituitary fossa, see sella turcica
Pituitary gland, 230
Pituitrin, 232
Plane coronal, 3
median, 2
sagittal, 2

transpyloric, 183, 270
transverse, 3
Plasma, 142
Platelets, 142
Pleura, 152

surface markings of, 268
Plicae circulares, see circular folds
Polymorphonuclear leucocytes, 141
Pons, 243

Popliteal artery, 135
Popliteal fossa, J17, 272
Portal circulation, 138
Portal fissure of liver, 200
Portal vein, 126
Pouch of Douglas, 186
Pregnancy, 227
Prepuce, 221
Process, 30

articular (vertebrae), 58
coracoid (of scapula), 74
coronoid (of mandible), 46
coronoid (of ulna), 79
mastoid, 39
odontoid, 59
spinous, 58

styloid (of radius^, 78
styloid (of temporal bone), 351.^
styloid (of ulna), 79
transverse, 58
xiphoid, 70
Progesterone, 231
Projections, radiogf^phic, 8
Prolactin, 231
Pronation, 87
Prone, 3

Prostate gland, 221
Protein, 207
Protoplasm, 4
Proximal, 1
Pseudopodium, 6
Ptyalin, 178
Puberty, 226, 239
Pubis, 90

Pulmonary circulation, 126
Pyloric antrum, 186
Pyramid of kidney, 212
Pyriform fossa, 179

Quadriceps fcmoris, 1 1 6

Radial artery, l33
notch of ulna, 79
Radiocarpal joint, see wrist joint
Radiographic appearances of;
abdomen, 183
ankle and foot, 104
biliary system, 203
cerebral arteries, 133
chest, 155
duodenum, 195
elbow region, 85
gall bladder, 203
genital tract, female, 227
genital tract, male, 220
heart, 125
hip region, 97
knee region, 100
large intestine, 196
shoulder region, 81
skull, 52

small intestine, 195
soft tissues of neck, 179
stomach, 194
urinary tract, 215
ventricular system of brain, 254
vertebral column, 66
wrist and hand, 88
Radio-ulnar joints, 85, 87
Radius, 78

Ramus, ascending, of jaw, 46
ischial, 91
pubic, 90

Receptaculum chyli, see cisterna chyli
Rectum, 192
Rectus sheath, 109
Red cells (of blood), 140
length of life of, 141
Reflex action, 250
Regions of the abdomen, 182
Renal arteries, 1 3 1
Rennin, 187
Reproduction, 6

INDEX

Reproductive systeim
feiwi«/221
male, 218
Respiration, 5,' 153
Reticulo-endothelial system, 166
Retina, 2S8
Ribs, 70

Rods and cones, 258

Sacrum, 68
Sacro-iliac joint, 92
Sagittal suture, 45
Saliva, 178
Salivary gland, 175
Saphenous vein, 138
Sartonus muscle, 1 15
Scaphoid bone of carpus, 80
Scapula, 75
Sclera, 257
Scrotum, 219
Sebaceous gland, 15
Sebum, 15
Sella turcica, 41
surface anatomy of, 266
Semen, 219

Semicircular canal, 262
Semilunar cartilage of knee, 100
Seminal duct, 220
Seminal vesicle, 220
Sensation, cutaneous, 263
Senses, special, 257
Sensory path, 250
Serum, 142
Sesamoid bone, 30
Shoulder joint, 80

Shoulder region, radiographic appeu
ances of, 81

Sight, mechanism of, 257
Sigmoid colon, 192
Sinus, coronary, 123
superior longitudinal, 136
transverse, 136
Sinuses, air, of skull, 49
Skeleton, 32
Skin, 13

Skull, base of, 43
fossae of, 43

radiographic appearances of, 52
surface anatomy of, 265
Small intestine, 187
Smell, sensation of, 263
Soft palate, 169
Speech, 243
Spermatozoon, 7
Sphenoidal bone, 41
Spinal accessory nerve, 246
column, see vertebral column
cord, 246
Spinal nerves, 246
Spine,

of ischium, 90
of scapula, 75
of tibia, 95

Spinous process of vertebra, 58
Spleen, 166

surface.anatomy of, 271
Splenic flexure of colon, 192

Squamous epithelium, 10
Stapes, 260

Sternoclavicular joint, 80
Sternomastoid muscle, 108
Sternum, ahgle of, 69
Stomach, 186

radiographic appearances of, 194
Striped muscle, 1 1
Styloid process of radius, 78
temporal bone, 39
of ulna, 79

Subarachnoid space, 252
Subclavian artery, 129
Sublingual salivary gland, 177
Submandibular salivary gland, 177
Subscapular fossa, 75
Subscapularis, 1 12
Succus entericus, 191
Sulcus, central, 243
lateral, 243
Superflcial fascia, 107
Superior vena cava, 128
Supination, 87
Suprarenal gland, 236
Supraspinatus muscle, 169
Surface anatomy of:
abdomen, 268
breast, 267

bifurcation of trachea, 268
bladder, urinary, 271
gall bladder, 270
head and neck, 265
heart, 267
kidneys, 271
larynx, 266
limbs, lower, 272
limbs, upper, 272
liver, 270
lung, 268
pancreas, 271
pleura, 268
sella turcica, 266
spleen, 271
sternal angle, 267
thyroid gland, 267
ureters, 271
uterus, 272
Suture, coronal, 45
lambdoid, 45
sagittal, 45
Swallowing, 197
Sweat, 16
Sweat glands, 1 5
Sympathetic nervous system, 252
Symphysis of mandible 46
of pubis, 90
Synovial joints, 33
membrane, 34
Systems, 12

Systemic circulation, 125
Talus, 96

Tarsus, bones of, 95
joints of, 102

radiographic appearances of, 104
Taste, 263
Tears, 259

INDEX

Teeth, 173
Temporal bone, 38
Temporomandibular joint, 46
Tendon, Achilles. 118
Tentorium of cerebellum, 2S2
Testis, 219
Thalamus, 242
Thenar eminence, 155
Thoracic duct, 158
Thorax, 69
great vessels of, 128
joints of, 72
Thymus, 235
Thyroid cartilage, 148
gland. 233

surface anatomy of, 267
Tibia, 94

Tibiofibuiar joint, inferior, 101
superior, 101
Tissues, 9
Tissue fluid, 158
Tongue, 169
Tonsil, lingual, 173
pharyngeal, 163, 179
Trachea, 149
Tract, spinal, motor, 249
sensory, 250

Transpyloric plane, 183, 270
Trapezium of carpus, 80
Trapezius muscle, 108
•Trapezoid of carpus, 80
Triceps brachii muscle, 113
Tricuspid teeth, 174
valve, 122

Trigeminal nerve, 246
Triquetral bone of carpus, 80
Trochanter, definition of, 32
greater, 92
lesser, 92

Trochlea of humerus, 77
Trochlear nerve, 245
Trochlear notch of ulna, 79
Trypsin, 189
Tube, auditory, 145
uterine, 224

Tubercle, adductor, of femur, 93
of rib, 71

Tubule, seminiferous, 219
uriniferous, 212
Tumours, 28
Tunnel, carpal, 88
Turbinate bone, see concha
Tympanic membrane, 260
antrum, 39

Ulceration, 28
Ulna, 79
Ulnar artery, 1 33
Umbilical region, 182
Umbilicus, position of, 270
Unstriped muscle, 1 1
Urea. 201
Ureter, 212
Urethra, female, 213
' male, 213
Urinary bladder, 212
system, 209

Urine, 214
Uterus, 222

surface anatomy of, 272
Uvula, 169

Vagina, 225
Vagus nerve, 246, 254
Vallecula, 179
Valves of heart, 122
Vas deferens, see seminal duct
Vasoconstriction, 16, 119
Vasodilatation, 16, 119
Vater, ampulla of, sec duodenal papilla
Vault of skull, see cranium
Vein, axillary, 137
azygos, 130
basilic, 136
cephalic, 136
femoral, 138
hepatic, 1 38, 200
inferior vena cava, 1 38
innominate, 129
internal jugular, 136
median cubital^ 136
popliteal, 138
portal, 139
pulmonary, 129
renal, 138
saphenous, 138
subclavian, 137

superior longitudinal sinus, 136
superior vena cava, 128
Veins, structure of, 120
Ventricles of heart. 122
of brain, 230
Venule, 1 19

Vermiform appendix, 191
Vertebral column, bones of, 58
joints of, 64

radiographic appearances of, 66
Vestibule of ear, 261
Villus, 189
Visceral pleura, 153
pericardium, 123
peritoneum, 184
Vital capacity of lungs, 154
Vitamins, 208
Vitreous humour, 258
Vocal cords, 148
Volume, expiratory reserve, 1 54
inspiratory reserve, 154
residual, 154
tidal. 154
Vulva, 225

Water, 206

White blood cells, 141
Willis, circle of, 1 32
Wrist joint, 87

Xiphoid process of sternum, 70

Zygom^, see malar bone
Zygomatic arch, 39